Synthesis of hydrous SnO2 and SnO2-coated TiO2 powders by the homogeneous precipitation method and their characterization

Hydrous SnO₂ and SnO₂-coated TiO₂ powders were synthesized by the homogeneous precipitation method using urea and the products were characterized by X-ray diffraction, thermogravimetry, differential thermal analysis, scanning electron microscopy and energy- dispersive X-ray microanalysis. Electrical conductivities were measured with an impedance analyser. Hydrous SnO₂ powder prepared under conditions without SO ₄ ^2– ions was a bulky product containing 75 wt% of water. The addition of SO ₄ ^2– ions to the solution changed bulky hydrous SnO₂ to a dense product; approximately spherical particles were obtained with an average particle size of 0.14 ± 0.03 m. with 13.5 wt % of absorbed water. Antimony-doped hydrous SnO₂ prepared under conditions with SO ₄ ^2– ions consisted of approximately spherical particles with an average particle size of 0.17 ± 0.04 m with 15.0 wt % of absorbed water. Hydrous SnO₂-coated TiO₂ powders with a good dispersion state and with various Sn/Ti ratios were prepared under conditions with SO ₄ ^2– ions. All the as-prepared coated powders were white, but the products doped with Sb³⁺ ions were turned to pale blue by heat treatment at 600° C for 1 h and their electrical conductivities increased by orders of about 3.0 in comparison with those of the other two.     

Organic–silicate hybrid catalysts based on various defined structures for Knoevenagel condensation

Two types of organic–inorganic hybrid base catalysts are prepared. Organic-functionalized molecular sieves (OFMSs), particularly “amine-immobilized porous silicates”, are designed based on common idea to immobilize catalytic active sites on silicate surface. Silicate–organic composite materials (SOCMs), such as “ordered porous silicate–quaternary ammonium composite materials”, are the precursors of ordered porous silicates obtained during the synthesis. Both the OFMS and the SOCM are used as the catalysts for Knoevenagel condensation. Among the OFMSs, there is clear tendency that the use of molecular sieve with larger pore volume and/or surface area gives the product in higher yield. Aminopropylsilyl (AP)-functionalized mesoporous silicates such as AP-MCM-41 gives the product in high yield under mild conditions. No loss of activity is observed after repeated use for three times. The SOCMs are also active for the same reaction. The precursors of the mesoporous silicates are more active than those of microporous silicates. This material can be repeatedly used without significant loss of activity. High activity is not due to the leached species. The active sites of the SOCM catalysts are considered to be SiO⁻ moieties located on the pore-mouth. Activity of the SOCM increases when the reaction is carried out without solvent, whereas decrease in activity of the OFMS is observed in the solvent-free system.     

Preparation of Self-Standing, Submillimeter-Thick Porous Titania Films with Anatase Nanocrystallites Using Evaporation-Induced Self-Assembly

Self-standing transparent submillimeter-thick (∼0.34 mm) mesoporous titania films were prepared using the evaporation-induced self-assembly (EISA) of a triblock copolymer template and titanium tetraethoxide. Performing EISA at low temperature and low humidity improved the transparency and continuity of the films. As synthesized films had a well-defined hexagonal mesostructure and the existence of both amorphous titania and anatase nanocrystallites (2 nm) was confirmed. The films that were calcined at 400°C were composed of anatase nanocrystallites (14–16 nm) and had a BET surface area of 90 m² g⁻¹ with 13-nm pores. The films were characterized using XRD, FE-SEM, TEM, and N² adsorption–desorption measurements. An erratum to this article can be found at     

Evaluating card-based protocols in terms of execution time

International Journal of Information Security - Card-based cryptography is an attractive and unconventional computation model; it provides secure computing methods using a deck of physical cards....     

Crossover from 3D to 2D metallic conduction in Sr2RuO4

We have investigated the normal-state conduction of superconducting Sr₂RuO₄ (T_c 1K), which is isostructural to La_2–xSr_xCuO₄. The resistivity of single crystals shows a crossover at T_M130K from 3D metallic conduction at lower temperatures to 2D one at higher temperatures. Concerning the temperature dependence of the out-of-plane resistivity, we present a systematic interpretation based on competition between the life time of the quasiparticles and the time for the quasiparticles to travel between the adjacent RuO₂ planes.     

Evaluation of environmentally friendly lubricants for cold forging

The authors proposed double-layer-type environmentally friendly lubricants, which were composed of an undercoat, superior in adhering to a material, and an overcoat, superior in reducing the friction between the material and the die. The performance of these lubricants for cold forging was evaluated by the ring compression test, the combined forward rod-backward can extrusion-type friction test and the combined forward conical can-backward straight can extrusion-type friction test. The double-layer-type lubricants showed comparable friction characteristics and anti-pick-up properties to a conversion coating lubricant, when the film thickness and surface treatment before coating were improved. In a practical application by cold multistage forging, the double-layer-type lubricants showed a similar performance to a conversion coating lubricant.     

Transistor Paint: Environmentally Stable N‐alkyldithienopyrrole and Bithiazole‐Based Copolymer Thin‐Film Transistors Show Reproducible High Mobilities without Annealing

New solution processable 4‐(2‐hexyldecan)‐4H‐bisthieno[2,3‐d:3′,2′‐b]pyrrole and 4,4′‐dialkyl‐2,2′‐bithiazole‐based copolymers (PBTzDTPs) are synthesized with excellent FET performance. These novel copolymers have considerable potential in printable electronics as they have high charge carrier mobilities, excellent air stability, good solution processibility, and no requirement for post‐deposition thermal annealing, all requirements for this field of application. The thin film transistors fabricated from PBTzDTPs achieve field effect mobilities as high as 0.14 cm² V^?1 s^?1 with current on/off ratios up to 10⁶ without thermal annealing. In addition, the devices exhibit stable performance in air, showing no significant degradation over 60 days. Moreover, the polymers described here provide an excellent example of the systems in which higher mobility performance does not require higher crystalline, long‐range ordered structures. Such a system appears to be particularly promising for rapid fabrication techniques, where kinetic conditions usually prevent the development of long‐range order.     

Effects of solid lubricants in backward extrusion

In the present paper, some solid lubricants were tested in backward extrusion friction tests with flat-headed punches using aluminium at room temperature. The results showed that anti-seizure ability was improved when wax was added to the solid lubricant samples. In addition, a water-based graphite lubricant and an ultrahigh molecular weight polyethylene (UHMW-PE) lubricant were tested using aluminium workpieces heated to 500°C. The lubricity of the UHMW-PE lubricant was found to be superior to that of the graphite lubricant.     

Experimental study on method of estimating strength of weld metal in steel structure

We conducted the welding experiment using three kinds of test piece, actual size, diaphragm and butt joint. Then, we examined the influence on strength, cooling time and carbon equivalent of weld metal by welding conditions on the different test pieces. We calculated an estimate of cooling time and chemical components. Consequently, we concluded that the strength of weld metal can be estimated by heat input, interpass temperature, carbon equivarent of welding wire and shape of test piece.