A Safe Way of Performing Some Dangerous Experiments. II. Construction of a Safety Dropper

Due to the high safety risks, chemistry instructors avoid demonstrating many remarkable experiments based on the addition of a liquid to a solid. Well-known examples of such demonstrations are various pyrotechnic mixtures of potassium chlorate and sugar (sucrose), which are usually activated with a drop of concentrated sulfuric acid. Other attractive demonstrations are the addition of water to freshly prepared magnesium phosphide and addition of water to burning magnesium. In all of these demonstrations the reaction that takes place immediately is very vigorous and can be hazardous for the instructor. Because chemistry teachers and instructors usually try to avoid performing experiments that include a hazard, a number of highly attractive experiments may remain unknown to the public. Using a simple homemade device called a safety dropper, one can perform all of these experiments with complete safety, both for the audience and the demonstrator. Details for performing some of these experiments as well as for the construction of the safety dropper are given in this paper. Video clips of demonstrations are included as an aid for inexperienced instructors.     

Electrocatalysis by foreign metal monolayers: Oxidation of formic acid on platinum

It was demonstrated that some foreign metal monolayers formed by underpotential deposition have pronounced catalytic effects on the oxidation of formic acid on platinum. The explanation of these effects was sought within the framewor of existing data on the formic acid oxidation and the underpotential deposition. It was found that the catalytic effect of foreign metal monolayers originates in the decrease of hydrogen adsorption thus preventing the formation of the main poisoning species COH. At the same time these experiments confirm the previously postulated mechanism of formation of the poisoning species involving adsorbed hydrogen.     

Optimization of the TLC Separation of Seven Amino Acids

JPC – Journal of Planar Chromatography – Modern TLC - A ternary mobile phase for thin-layer chromatographic separation and identification of seven amino acids on microcrystalline...     

A Study of Amorphous Precursors for PbZrO3-PbTiO3 Based Ceramic Materials

Amorphous precursors for PbZrO₃ and PbTiO₃ ceramics were prepared from lead acetate and the transition metaln-propoxide inn-propanol orn-butoxide inn-butanol and hydrolysed with an excess of water. According to GLC and TGA/EGA analyses, the type of alkoxide group influences distinctly the structure of heterometallic precursors, i.e., oxo or acetate bridging, and the amounts of hydroxyl and organic groups bound to the metal network. The local environments of metal atoms in the amorphous precursors were also studied by EXAFS. The analysis reveals that in Pb−Zr precursors alkoxide groups modify the coordination spheres of the zirconium atoms. Conversely, local environments of both lead and titanium atoms within the analysed range of 3.4 A depend weakly on the type of alkoxide used.     

Interpretation of toroidal current and loop voltage temporal evolution during RF-current drive experiment on the T-7 tokamak

A simple analytical model is developed and solved to describe time evolution of the loop voltage and toroidal current when RF and inductive current drive take place simultaneously. A relation for the real value of the RF driven current has been obtained under these conditions. Comparison with experimental data from T-7 tokamak allows to estimate the role of the skin effect during RF current drive.The authors would like to thank A. Ya. Kislov for the basic data on the T-7 tokamak transformer. They are also indebted to V. V. Parail and G.V. Pereverzev for many clarifying discussions.     

New look at Gleason's theorem for signed measures

It is shown that the Gleason theorem holds not only for a finite but also for ann-finite signed measurem, wheren is a cardinal, defined on all closed subspaces of a Hilbert space whose dimension is a nonmeasurable cardinal 2, ifm is bounded from below on all one-dimensional subspaces.     

Some features of solar wind protons, α particles and heavy ions behaviour: The Prognoz 7 and Prognoz 8 experimental results

The paper describes the results of investigations of the solar wind ions, carried out on board the high apogee Prognoz 7 and Prognoz 8 Earth's satellites with the aid of an SKS instrument (USSR) and a Monitor instrument (USSR-SSR). Behaviour of proton and that of components on the front of Earth's bow and interplanetary shock waves were compared by means of the energoanalysis and energy-mass analysis techniques. In several long-term periods of observation the solar wind heavy ions — oxygen, silicon and iron were determined. It enabled us to estimate the solar corona chemical composition and electron temperature.Presented at the 5th General Assembly IAGA/IAMAP August 5–17, 1985, Prague, Czechoslovakia.     

Temperature dependence of development of slip bands and of strain hardening in AgCl crystals

The dependence of the flow stress and the slip band density on the plastic strain has been measured at 201 K, 293 K and 363 K. The growth of deformation concentrated in an average slip band has been stated. The types of obstacles acting against the rise and development of a slip band and the temperature dependence of the strain hardening in AgCl crystals are discussed. An equation stating the dependence of the flow stress on the slip band density is presented. The hardening in AgCl crystals is classified as the stage III — hardening.     

Hahn-Jordan decomposition for gleason measures

The possibility of the Hahn-Jordan decomposition forn-finite signed measures, wheren is a cardinal, defined on a quantum logic of all closed subspaces of a Hilbert space whose dimension is a nonmeasurable cardinal 2, is investigated.     

Dynamical systems with relaxation time

We define mathematically a class of dynamical systems that exhibit relaxation corresponding to that observed in physical systems, and then show that this class is identical with the class ofK-mixing dynamical systems.