Thermal patterns in evaporating liquid

In this paper, some of the preparatory experiments of the ESA sponsored space program CIMEX-1 are presented. A liquid layer of variable thickness is subject to a flow of inert gas. The non-uniform evaporation induced by the gas flow creates a temperature gradient parallel to the interface triggering in that way thermocapillary convection. The combined action of evaporation, thermocapillarity and gravity has been not completely clarified both theoretically and experimentally. The experiment presented in this work concerns a liquid layer of ethanol of 2.2 mm thickness in presence of a mass flow of Nitrogen whose intensity varies in the range of hundreds of milliliter per minute. The experiments were performed at an initial liquid temperature of 21°C. The patterns observed are strongly dependent on the flow rate of inert gas. A change in the instability patterns has been observed for a gas flow of about 1.7 l/min.     

Condensation on curvilinear fins (effect of groove flooding): EMERALD experiment of ESA

Some aspects of the ESA space program EMERALD are presented. A problem of the film type condensation on curvilinear fin is considered with taking into account the essential influence of the capillary forces and non uniform temperature of the fin. Disjoining pressure effect on condensate film flow is studied numerically, because of very thin film of condensate on the fin tip. Value of the groove flooding depth changes significantly the condensate outflow from the condenser. Calculations for water condensation predict a very high value of the heat transfer coefficient, more than 50 kW/m²K, on a quite important part of the surface area and confirm the idea of proposed condenser and Double Capillary Pumped Loop.     

Modeling of Porous Rock: Digitization and Finite Elements Versus Approximate Schemes Accounting for Pore Shapes

We consider connections between microstructure and elastic properties of porous/microcracked materials on the example of Fontainebleau sandstone. The microstructural information (average shapes of pores) required for adequate modeling of the isotropic elastic properties is identified. It is shown that, if this information is utilized, the usual effective media schemes provide satisfactory predictions of the effective elastic properties.     

Fabrication of ZnO nanorod-based hydrogen gas nanosensor

We report a first work on nanofabrication of hydrogen nanosensor from single ZnO branched nanorods (tripod) using in-situ lift-out technique and performed in the chamber of focused ion beam (FIB) system. Self-assembled ZnO branched nanorod has been grown by a cost-effective and fast synthesis route using an aqueous solution method and rapid thermal processing. Their properties were analyzed by X-ray diffraction, scanning electron microscopy, energy dispersion X-ray spectroscopy, transmission electron microscopy, and micro-Raman spectroscopy. These analyses indicate high quality ZnO nanorods. Furthermore, our synthesis technique permits branched nanorods to be easily transferred to other substrates. This flexibility of substrate choice opens the possibility of using FIB system for handling.

The main advantage of the proposed in-situ approach is a controllable lift-out procedure which permitted us to obtain a 90% success rate for building nanodevices. The fabricated nanosensor uses only single self-assembled ZnO branched nanorod (tripod) to gauge the 150 ppm H₂ in the air at room temperature. The hydrogen sensitivity is in the range of 0.6–2% depending on which two branches to use. The nanosensor has selectivity against other gases such as O₂, CH₄, CO and LPG, which shows sensitivity of <0.02%. The single ZnO branched nanorod sensor can operate at low power of <5 μW.     

Optical monitoring of characteristics of the stratospheric aerosol layer and total ozone content at the Siberian Lidar Station (Tomsk: 56° 30′ N; 85° E)

We consider the results of long-term remote optical monitoring obtained at the Siberian Lidar Station of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk (56° 30′ N, 85° E). The scattering characteristics of stratospheric aerosol layer, obtained according to data of lidar measurements recorded since 1986, are presented. We analyse the trends of changes in the total ozone (TO) content over Tomsk for the period 1996–2013 according to data of spectrophotometric measurements employing Total Ozone Mapping Spectrometer (TOMS) data for the period 1979–1994. We determined the periods of elevated content of stratospheric aerosol over Tomsk after a series of explosive eruptions of volcanoes in the Pacific Ring of Fire and Iceland in 2006–2011. Since the second half of the 1990s we have recorded an increasing TO trend, equalling 0.65 DU/year for the period 1996–2013.     

Oxidation of ZrB2–SiC–ZrSi2 ceramics in oxygen

The oxidation of ZrB₂–SiC and ZrB₂–SiC–ZrSi₂ ceramics of different composition has been studied experimentally at 1500 °C in pure oxygen for up to 50 h. ZrB₂–SiC–ZrSi₂ ceramics proved to be the most oxidation-resistant at ZrSi₂ contents of less then 4 wt%. These ceramics were more oxidation-resistant than ZrB₂–SiC ceramics. An analytical model of growth kinetics for a multilayered scale based on an oxidation–diffusion balance was developed and tested.     

Novel hydrogen gas sensor based on single ZnO nanorod

For extensive use in an industrialized process of individual ZnO nano/microrods as building nanoblock in novel hydrogen sensors, a simple, inexpensive, and bio-safe synthesis process and nanofabrication route is required. Here, we report a cost-effective and fast synthesis route for ZnO one-dimensional nanorod using an aqueous-based approach in a reactor. Our synthesis technique permits nano/microrods to be easily transferred to other substrates and to be distributed on the surface. This flexibility of substrate choice opens the possibility of using focused ion beam (FIB/SEM) system for handling and fabricating nanosensors. The main advantage of this procedure is a quick verification/testing of concept and is compatible with micro/nanoelectronic devices. The described nanofabrication steps permitted us to obtain a 90% success rate for building single nanorod sensor. A sensitivity of ∼4% was obtained for a single ZnO nanorod hydrogen sensor at 200 ppm H₂ in the air at room temperature. The nanosensor has a high selectivity for H₂, since its sensitivity for O₂, CH₄, CO, ethanol or LPG are less than 0.25%.     

Vapor Condensation on Curvilinear Disk-Shaped Fin at Microgravity

A problem of the film type condensation of the pure vapor on disk-shaped fin is considered with taking into account the essential influence of the capillary forces. Calculations for FC-72 condensation on such fin have been performed at microgravity conditions. A hump on the condensate film thickness curve is occurred on the concave part of the fin due to the additional curvature of the disc shape. The results have been compared to results for straight fin with the same surface area of condensation. Condensate outflow from the disk-shaped film is greater than from straight fin.     

Sonochemical Preparation and Properties of Pt–3Y-TZP Nano-Composites

A uniformly aggregated 3 mol% yttria-stabilized tetragonal zirconia nano-powder (3Y-TZP) was prepared using thermal hydrolysis and the ultrasonic deagglomeration technique. The possibility of nano-engineering of Pt–3Y-TZP composite aggregates was studied. The as-synthesized Pt nano-particles (∼2 nm) were impregnated into zirconia nano-aggregates (20–45 nm). The morphology manipulation technique allowed production of the composite zirconia-based aggregates in which a significant fraction of the Pt particles was embedded into the densified zirconia aggregates. Using the colloidal technique and low-temperature (1150°C) sintering, we prepared the Pt-zirconia (0.5–1.5 wt% of platinum) nano-composites with average 3Y-TZP grain sizes of 120 nm, and with the platinum grains size in the range of 20–60 nm. The catalytic properties of composite Pt–3Y-TZP nano-composites were studied and described.     

Alkynes Carbonylation Reactions in Solutions of Palladium Complexes as a New Class of Oscillatory Processes

This article dedicated to study of few oscillating reactions in homogeneous systems. The experimental data and preliminary mechanism are reported. The authors affirm they find new type of oscillating processes—the reactions of carbonylation.