Electrochemical chlorination of ethyl acetoacetate and the formation of ethyl 2,2,4-trichloroacetoacetate

Conclusions The electrochemical chlorination of ethyl acetoacetate in aqueous media proceeds at C² and, partially, at C⁴ to give ethyl 2,2-dichloroacetoacetate and small amounts of ethyl 2,2,4-trichloroacetoacetate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 876–877, April, 1988.     

Biological activity of detonation nanodiamond and prospects in its medical and biological applications

The present review summarizes and analyzes recent advances in the field of medical and biological applications of detonation nanodiamond and, on this basis, considers most promising ways of creation of anticancer and antimicrobial drugs, diagnostic agents, and nanocompositions for orthopedic surgery. In addition, progress in the surface chemistry of detonation nanodiamond is discussed and problems related to purposeful surface modification with a view to obtain detonation nanodiamond with desired properties ensuring their successful application in biology and medicine are considered.     

Cluster self-organization of inorganic crystal-forming systems: Templated nanocluster precursors and self-assembly of framework MT structures of A/B,Zr silicates (A = Na, K; B = Ca, Sr)

The basic concepts that are used to describe crystallization as a phenomenon of the hierarchical (cluster) self-organization of a chemical system are considered. The templation of theoretically possible nan-ocluster precursors composed of M octahedra and T tetrahedra by atoms of (A) alkaline and (B) alkaline earth metals is considered for the first time. A relationship between the A/B,M,T composition of templated nanocluster precursors with the composition of A/B,M silicates is established. The model that is developed is used to search for nanocluster precursors in framework MT structures of A/B,Zr silicates. Computer methods (TOPOS 4.0 program package) were used to perform complete 3D reconstruction of the self-assembly of all (four) structural types of A/B,Zr silicates (A = Na, K; B = Ca, Sr) with frameworks of the MT ₂O₇ type: nan-ocluster precursor S ₃⁰-primary chain S ₃¹-microlayer S ₃²-microframework S ₃³. The invariant type of mono-cyclic nanocluster precursor M ₂ T ₄ (with the point symmetries [`1]\bar 1 and 2), stabilized by one or two template cations (A and B), is determined. Bifurcations of the paths of evolution at the S ₃¹ level (structural branching point) are established for the self-assembly of the following frameworks: MT-1 in CaZrSi₂O₇ (gittinsite, C2), MT-2 in SrZrSi₂O₇ (P2₁/c); MT-3 in Na₂ZrSi₂O₇ (parakeldyshite,), K₂ZrSi₂O₇ (khibinskite, P2₁/b), and K₂ZrGe₂O₇ (C2/c); and MT-4 in Na₂ZrSi₂O₇ (H₂O)(C2/c), Na₃ScSi₂O₇ (Pbnm), and K₃ScSi₂O₇ (P6₃/mmc).     

The 100th anniversary of the discovery of X-ray diffraction

A general historical essay on studies related to the discovery of X-ray diffraction, beginning with the first works by W.C. Roentgen, W. Friedrich, P. Knipping, and M. Laue, is presented. The coming of age of X-ray diffraction as an efficient tool for determining crystal structure is considered. The pioneering studies by W.G. Bragg, W.L. Bragg, Yu.V. Wulf, and E.C. Fedorov are briefly reviewed. The contribution of the Russian scientific school to the development of X-ray studies is indicated. The modern state and the directions of development of X-ray physics are discussed.     

Cluster self-organization of intermetallic systems: Nanocluster precursors (i-K8, i-K6, K4) and self-assembly of crystal structures Ir8Mg58(cF396), Ir7Mg44(cF408), and Ir6Mg26 (hR96)

Suprapolyhedral cluster precursors Kn with a hierarchical structure (with the number of polyhedra n = 4, 6, 8) have been derived and their topological representation as bichromatic graphs has been performed. With the use of computer methods (the TOPOS program package), combinatorial-topological analysis of icosahedral monster structures of close compositions Ir₈Mg₅₈ (cF396, F $ \bar 4 $ 3m, V = 8139 ų) and Ir₇Mg₄₄ (cF408, F $ \bar 4 $ 3m, V = 8117 ų) has been performed. Suprapolyhedral nanoclusters consisting of eight and six Ir icosahedra (nanoclusters i-K8 and i-K6 comprising 86 and 50 atoms) have been identified by the method of complete decomposition of the 3D factor graph of crystal structures into cluster substructures in Ir₇Mg₄₄. In Ir₈Mg₅₈, the i-K8 nanocluster is retained, whereas the i-K6 cluster is substituted by the K4 nanocluster composed of four Ir polyhedra with CN = 9 comprising 34 atoms. Complete 3D reconstruction of the self-assembly mechanism of crystal structure has been carried out by the scheme nanocluster precursor-primary chain-microlayer-microframework. It has been demonstrated that the voids in the Ir₈Mg₅₈ and Ir₇Mg₄₄ frameworks accommodate tetrahedral cluster spacers T-Mg(Mg₄) and T-Mg₄, respectively. The Ir₆Mg₂₆ structure (hR96, R $ \bar 3 $ c, V = 1890 ų) is made of the suprapolyhedral cluster K6 formed by six Ir polyhedra with CN = 11 and comprising 50 atoms; in this case, the structure contains no cluster spacers. In all structures, nanoclusters retain their own symmetry ( $ \bar 4 $ 3m for i-K8, i-K6, and K4 and $ \bar 3 $ for K6).     

Intermetallic Compounds LikMn (M = Ag,Au, Pt,Pd, Ir,Rh): Geometrical and Topological Analysis,Tetrahedral Cluster Precursors,and Self-Assembly of Crystal Structures

Crystallography Reports - A combinatorial and topological analysis has been performed and self-assembly of the crystal structures of intermetallic compounds formed in the Li–M (M = Ag, Au,...     

Hyperfine magnetic interactions in Tb(Fe1 − x Al x )2 alloys

The structural and magnetic characteristics of phase transformations in Tb(Fe_{1 ? x} Al _x )₂ alloys with concentrations x = 0?0.9 have been measured in the temperature range from 90 to 450 K. The temperature dependences of the hyperfine magnetic fields for each of local configurations of the nearest environment of iron atoms upon substitution of aluminum atoms for iron atoms have been found using Mössbauer spectroscopy.     

Some aspects of the effect of aluminum and its compounds on living organisms

The data on toxicity of aluminum compounds to various organisms were collected and summarized. The problems of occupational diseases in workers exposed to aluminum compounds in the production process were considered. The data of experimental researches on animals obtained for different aluminum compounds were summarized.     

X-ray,Mössbauer,and magnetic research of system Y(Fe<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Al<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)<Subscript>2</Subscript> alloys

The structural transformations and magnetic phase transitions in the quasibinary system Y(Fe_{1 ? x} Al _x )₂ have been investigated by Mössbauer spectroscopy, X-ray diffractometry, and magnetic measurements of polycrystals.