Study of dynamics of drying processes in FE2O3 and SIO2 nanocolloid droplets

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.This work is devoted to comparison of changes in geometry and in light transmittance of evaporating drop of nanocolloid deposited on flat surface. One of the focuses of paper is aimed at differentiation of drying process into separate stages, each being characterized by particular behavior of suspension nanoparticles inside the droplet, the last of which ends by forming of ring-shaped patterns (known as “coffee ring effect”) that appear after all the fluid has evaporated. Dynamics of colloids` evaporation was studied according to two observing techniques. The first one was based on spectrometric measuring of light transmitted through droplets. The second method was based on registering of geometrical properties of drying puddles that were changing in time due to evaporation. Patterns left by droplets of nanocolloids were alike in general – collars were formed along the perimeter of initial droplet. According to coffee ring effect a major part of suspended particles assembled in these collars though a thin film of suspended substance deposited within initial drop perimeter. The results of drying dynamics experiments carried out in two different techniques appeared to be also different. The second (geometrical) method showed a uniform decrease of drop height while the first (spectrometric) method showed non-uniform changing of parameters. The time of drying according to the second technique was less than the time of drying received in experiments undertaken with the first technique.cf201

Вплив молекулярної маси гідроксипропілцелюлози на реологічні властивості водо-етанольних суспензій вугілля

The rheological properties of aqua-ethanol-coal of varying degrees coal metamorphism, stabilized by macromolecular surfactants was studied by rotational viscometry. It was found that including of hydroxypropylcellulose as a stabilizer for dispersions of coal and water-ethanol mixtures, increasing their stability. It is shown that with increasing molecular weight of  hydroxypropylcellulose viscosity of disperse systems increases, regardless of the degree of coal metamorphism. With increasing concentrations of the polymer injected more than 0.01 % of coal the viscosity of the systems increases sharply.Методом ротаційної віскозиметрії досліджено реологічні властивості водо-етанольних суспензій вугілля різного ступеня метаморфізму, стабілізованих високомолекулярними поверхнево-активними речовинами. З’ясовано, що при введені гідроксипропілцелюлози, в якості стабілізатора до дисперсій вугілля і водо-етанольної суміші, підвищується їх стабільність. Показано, що при зростанні молекулярної маси гідроксипропілцелюлози в’язкість дисперсних систем зростає, незалежно від ступеня метаморфізму вугілля. При збільшенні концентрації введеного полімеру більш ніж 0,01 % в розрахунку на масу вугілля різко зростає в’язкість досліджуваних систем

Link between shear modulus and enthalpy changes of Ti16.7Zr16.7Hf16.7Cu16.7Ni16.7Be16.7 high entropy bulk metallic glass

Mechanical and thermal properties of materials are intricately linked. Particularly, this fully applies to metallic glasses. In this work, we study shear modulus behavior and heat effects occurring upon heating up of Ti16.7Zr16.7Hf16.7Cu16.7Ni16.7Be16.7 high entropy bulk metallic glass up to the full crystallization. In the framework of the Interstitialcy theory, we show that shear modulus relaxation data can be applied to quantitatively predict exo- and endothermal effects related to structural relaxation, glass transition and crystallization of this high entropy metallic glass. This fact suggests that the underlying physical mechanism responsible for this link can be conditioned by the relaxation of the system of structural defects, which by their properties are similar to dumbbell interstitials in metals.Peer ReviewedPostprint (author's final draft

The Atmospheric Chemistry Suite (ACS) of Three Spectrometers for the ExoMars 2016 Trace Gas Orbiter

The Atmospheric Chemistry Suite (ACS) package is an element of the Russian contribution to the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission. ACS consists of three separate infrared spectrometers, sharing common mechanical, electrical, and thermal interfaces. This ensemble of spectrometers has been designed and developed in response to the Trace Gas Orbiter mission objectives that specifically address the requirement of high sensitivity instruments to enable the unambiguous detection of trace gases of potential geophysical or biological interest. For this reason, ACS embarks a set of instruments achieving simultaneously very high accuracy (ppt level), very high resolving power (>10,000) and large spectral coverage (0.7 to 17 μm—the visible to thermal infrared range). The near-infrared (NIR) channel is a versatile spectrometer covering the 0.7–1.6 μm spectral range with a resolving power of ∼20,000. NIR employs the combination of an echelle grating with an AOTF (Acousto-Optical Tunable Filter) as diffraction order selector. This channel will be mainly operated in solar occultation and nadir, and can also perform limb observations. The scientific goals of NIR are the measurements of water vapor, aerosols, and dayside or night side airglows. The mid-infrared (MIR) channel is a cross-dispersion echelle instrument dedicated to solar occultation measurements in the 2.2–4.4 μm range. MIR achieves a resolving power of >50,000. It has been designed to accomplish the most sensitive measurements ever of the trace gases present in the Martian atmosphere. The thermal-infrared channel (TIRVIM) is a 2-inch double pendulum Fourier-transform spectrometer encompassing the spectral range of 1.7–17 μm with apodized resolution varying from 0.2 to 1.3 cm−1. TIRVIM is primarily dedicated to profiling temperature from the surface up to ∼60 km and to monitor aerosol abundance in nadir. TIRVIM also has a limb and solar occultation capability. The technical concept of the instrument, its accommodation on the spacecraft, the optical designs as well as some of the calibrations, and the expected performances for its three channels are described

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

Furan Oxidation Reactions in the Total Synthesis of Natural Products

Recent developments on the transformations of furans under oxidative conditions toward the total synthesis of complex natural compounds are discussed. Reactions and methods are classified according to the type of oxidant used. Comparisons are then made between all the strategies to provide a comprehensive overview. This review covers the most prominent work published from 2011 until 2017. 1 Introduction 2 Reagents and Methods for Oxidation of the Furan Ring 2.1 Singlet Oxygen 2.2 Peroxides and Hydroperoxides 2.3 Quinones 2.4 Halogen-Based Oxidants 2.5 Chromium-Based Oxidants 3 The Achmatowicz Reaction 3.1 Halogen-Based Oxidants 3.2 Hydroperoxides 3.3 Enzymatic Oxidation 4 Conclusion. © Georg Thieme Verlag Stuttgart. New York

Furan Oxidation Reactions in the Total Synthesis of Natural Products

Recent developments on the transformations of furans under oxidative conditions toward the total synthesis of complex natural compounds are discussed. Reactions and methods are classified according to the type of oxidant used. Comparisons are then made between all the strategies to provide a comprehensive overview. This review covers the most prominent work published from 2011 until 2017. 1 Introduction 2 Reagents and Methods for Oxidation of the Furan Ring 2.1 Singlet Oxygen 2.2 Peroxides and Hydroperoxides 2.3 Quinones 2.4 Halogen-Based Oxidants 2.5 Chromium-Based Oxidants 3 The Achmatowicz Reaction 3.1 Halogen-Based Oxidants 3.2 Hydroperoxides 3.3 Enzymatic Oxidation 4 Conclusion. © Georg Thieme Verlag Stuttgart. New York