Mandelbrot set in coupled logistic maps and in an electronic experiment

We suggest an approach to constructing physical systems with dynamical characteristics of the complex analytic iterative maps. The idea follows from a simple notion that the complex quadratic map by a variable change may be transformed into a set of two identical real one-dimensional quadratic maps with a particular coupling. Hence, dynamical behavior of similar nature may occur in coupled dissipative nonlinear systems, which relate to the Feigenbaum universality class. To substantiate the feasibility of this concept, we consider an electronic system, which exhibits dynamical phenomena intrinsic to complex analytic maps. Experimental results are presented, providing the Mandelbrot set in the parameter plane of this physical system.Comment: 9 pages, 3 figure

Spin excitations in the Fractional Quantum Hall regime at ν≲1/3\nu\lesssim1/3

We report inelastic light scattering experiments in the fractional quantum Hall regime at filling factors $\nu\lesssim1/3$. A spin mode is observed below the Zeeman energy. The filling factor dependence of the mode energy is consistent with its assignment to spin flip excitations of composite fermions with four attached flux quanta ($\phi$=4). Our findings reveal a composite fermion Landau level structure in the $\phi$=4 sequence.Comment: 7 pages, 4 figures, EP2DS-16 conference, to appear in Physica

A REVIEW ON METHODS OF COAL FLY ASH RARE EARTH ELEMENTS CONTENT AND PARTICLE SIZE DISTRIBUTION CONTROL

Приведены сведения о существующих методах определения содержания редкоземельных элементов и гранулометрического состава золы, образующейся при сжигании углей. Показано, что для точного определения содержания редкоземельных элементов целесообразно сочетание методов масс-спектрометрии и атомно-эмиссионной спектроскопии, а для контроля гранулометрического состава – применение метода лазерной дифракции.It is given the information on the existing methods for determining the content of rare earth elements and particle size distribution for coal fly ash. It is shown that a combination of mass spectrometry and atomic emission spectroscopy is expedient for precision determination of the content of rare earth elements, and the use of laser diffraction is used to control the particle size distribution

Mechanically activated catalyst mixing for high-yield boron nitride nanotube growth

Boron nitride nanotubes (BNNTs) have many fascinating properties and a wide range of applications. An improved ball milling method has been developed for high-yield BNNT synthesis, in which metal nitrate, such as Fe(NO(3))(3), and amorphous boron powder are milled together to prepare a more effective precursor. The heating of the precursor in nitrogen-containing gas produces a high density of BNNTs with controlled structures. The chemical bonding and structure of the synthesized BNNTs are precisely probed by near-edge X-ray absorption fine structure spectroscopy. The higher efficiency of the precursor containing milling-activated catalyst is revealed by thermogravimetric analyses. Detailed X-ray diffraction and X-ray photoelectron spectroscopy investigations disclose that during ball milling the Fe(NO(3))(3) decomposes to Fe which greatly accelerates the nitriding reaction and therefore increases the yield of BNNTs. This improved synthesis method brings the large-scale production and application of BNNTs one step closer

ON REGULATORY DOCUMENTATION IN THE FIELD OF ASH AND SLAG FROM COAL COMBUSTION FOR RARE EARTH ELEMENTS EXTRACTION

This article reviews the existing situation with regulatory documents on the use of ash and slag waste from coals combustion. The necessity of developing technical conditions for the use of this raw material for the extraction of rare earth elements is shown.В настоящей статье рассмотрена ситуация с состоянием нормативных документов по использованию золошлаковых отходов сжигания углей. Показана необходимость разработки стандартов по использованию этого сырья для извлечения редкоземельных элементов

CONTROL OF POLYACRYLAMIDE FLOCCULANTS CONCENTRATION IN THE PROCESS WATER

This article reviews the methods of polyacrylamide flocculants concentration control in process water. It is concluded that fluorescence method, ultraviolet spectroscopy and nephelometry are the most promising for continuous monitoring of low concentrations of flocculants, about 100 mg/m3, and the Wheatstone bridge is the most suitable measuring circuit.В настоящей статье рассмотрены методы определения концентрации полиакриламидных флокулянтов в воде. Сделан вывод о том, что для непрерывного контроля малых концентраций флокулянтов, порядка 100 мг/м3, наиболее перспективными являются: флуоресцентный метод, ультрафиолетовая спектроскопия и нефелометрия, а измерительной схемой – автоматический уравновешенный мост

Recent progress and perspectives of space electric propulsion systems based on smart nanomaterials

Miniaturized spacecraft built from advanced nanomaterials are poised for unmanned space exploration. In this review, the authors examine the integration of nanotechnology in electric propulsion systems and propose the concept of self-healing and adaptive thrusters

Dislocations and Grain Boundaries in Two-Dimensional Boron Nitride

A new dislocation structure-square-octagon pair (4|8) is discovered in two-dimensional boron nitride (h-BN), via first-principles calculations. It has lower energy than corresponding pentagon-heptagon pairs (5|7), which contain unfavorable homo-elemental bonds. Based on the structures of dislocations, grain boundaries (GB) in BN are investigated. Depending on the tilt angle of grains, GB can be either polar (B-rich or N-rich), constituted by 5|7s, or un-polar, composed of 4|8s. The polar GBs carry net charges, positive at B-rich and negative at N-rich ones. In contrast to GBs in graphene which generally impede the electronic transport, polar GBs have smaller bandgap compared to perfect BN, which may suggest interesting electronic and optic applications

Single step process for the synthesis of carbon nanotubes and metal/alloy-filled multiwalled carbon nanotubes

A single-step approach for the synthesis of multi-walled nanotubes (MWNT) filled with nanowires of Ni/ternary Zr based hydrogen storage alloy has been illustrated. We also demonstrate the generation of CO-free hydrogen by methane decomposition over alloy hydride catalyst. The present work also highlights the formation of single-walled nanotubes (SWNT) and MWNTs at varying process conditions. These carbon nanostructures have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), Energy dispersive X-ray analysis (EDX) and Raman spectroscopy. This new approach overcomes the existing multi-step process limitation, with possible impact on the development of future fuel cell, nano-battery and hydrogen sensor technologies