Synthesis and properties of high-pressure phase [Er<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Cu<Subscript>3</Subscript>](V<Subscript>4</Subscript>)O<Subscript>12</Subscript>

A new perovskite-like compound Er_0.73Cu₃V₄O₁₂ (space group Im \(\bar 3\), Z = 2, a = 7.266 Å) has been synthesized barothermally (P = 8.0 GPa, t = 1000°C). Its electrical and magnetic properties have been studied. It is found that the temperature dependence of the electrical conductivity (in the range 78–300 K) has of semiconductor type. The behavior of the impedance and admittance has been analyzed at 290 K and frequencies of 200 Hz to 200 kHz under atmospheric pressure and at high (15–42 GPa) pressures.     

Edge-minimization of non-deterministic finite automata

In this paper we consider non-deterministic finite Rabin-Scott’s automata. We use a special structure to describe all the possible edges of non-deterministic finite automaton defining the given regular language. Such structure can be used for solving various problems of finite automata theory. One of these problems is edge-minimization of non-deterministic automata. As we have not touched this problem before, we obtain here two versions of the algorithm for solving this problem to continue previous series of articles.     

Dependence of the anticancer activity of 1,3‐oxazole derivatives on the donor/acceptor nature of his substitues

A series of new 1,3‐oxazole derivatives, containing in position 5 both donor and acceptor substituents were synthesized. These substances were considered as potentially active anticancer pharmacophores in the human tumor cell line panel derived from nine cancer types, including lung, colon, melanoma, renal, ovarian, brain, leukemia, breast, and prostate. Primary in vitro one‐dose anticancer screening was shown that compounds with acceptor substituents (such as –C(O)OMe, –CN) in the position 5 inhibit the growth of most cell lines, and compounds with donor substituents (such as –NHR, ?SR) in the position 5 do not practically inhibit the growth of cancer cell lines. It can be assumed that the pharmacological activity of 1,3‐oxazole derivatives depends on donor/acceptor nature of the substituents in position 5. It was proposed to evaluate the donor/acceptor ability of 1,3‐oxazole derivatives using the special parameter φ₀, which takes into account the relative position of the boundary levels (HOMO end LUMO). The quantum‐chemical modeling was performed; the special parameter φ₀ for 1,3‐oxazole derivatives correlates with the experimental results. Quantum‐chemical calculations of the special parameter φ₀ allow modeling the pharmacological activity of 1,3‐oxazole derivatives by introducing donor or acceptor substituents at position 2 or 5. This work may be useful for chemists to develop a target synthesis of potential biologically active compounds.     

Assessing the structure of recycled polyethylene-modified bitumen using the calorimetry method

Journal of Thermal Analysis and Calorimetry - The thermo-physical properties enhancement of nanolubricants can improve the heat transfer performance in refrigeration system. In this study,...     

Unexpected photochemical transformation of imidazole derivatives containing the 5-hydroxy-2-methyl-4H-pyran-4-one moiety. Environmentally friendly method for the synthesis of substituted imidazo[1,5-a]pyridine-5,8-diones

An unexpected photochemical transformation of imidazole derivatives containing the 5-hydroxy-2-methyl-4H-pyran-4-one moiety was discovered, which led to the synthesis of previously unknown imidazo[1,5-a]pyridine-5,8-dione derivatives. The structures of imidazole and imidazo[1,5-a]pyridine-5,8-dione derivatives were unambiguously determined by X-ray diffraction analysis.     

Suppressing aggregation in a large polycyclic aromatic hydrocarbon

With the approach presented herein, a large aromatic pi-system is synthesized, which shows extraordinarily high solubility and an effective suppression of aggregation. This was due to a distortion of the aromatic core by bulky tert-butyl groups and the solubilizing effects of alkyl chains in the corona of the aromatic core. Therefore not only the processing and cleaning of the materials with standard laboratory techniques became possible, but moreover the first structure-rich UV/vis and a resolved (1)H NMR spectra for an aromatic system two times larger than hexa-peri-hexabenzocoronene were recorded. The bulk properties in an extruded fiber as well as on the surface showed a columnar self-assembly including a phase in which a homeotropic alignment on a substrate was observed, which turns the material into an interesting candidate for future applications in electronic devices.     

磁性碳纳米管表面新型壬基酚印迹纳米复合材料制备及吸附性能

采用聚苯胺包覆的磁性多壁碳纳米管为载体,以壬基酚(NP)为模板分子,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂制备新型磁性壬基酚印迹复合萃取材料。 采用扫描电子显微镜(SEM)、红外光谱(FT-IR)和样品振动磁强计(VSM)等技术手段对该磁性印迹复合材料进行表征和分析,结果表明,在磁性碳纳米管表面成功接枝厚度为60~70 nm的印迹聚合层。 采用高效液相色谱(HPLC)技术对该印迹复合材料的吸附性能进行探讨,结果表明,该磁性印迹复合材料对壬基酚具有特异性吸附性能,最大吸附量为38.46 mg/g。 结合HPLC检测技术,该磁性印迹复合材料成功用于分离富集饮用水中的壬基酚。     

Nanostructured, Gd-doped ceria promoted by Pt or Pd: investigation of the electronic and surface structures and relations to chemical properties

Nanostructured ceria doped with other rare earth elements is a good oxygen ion conductor, which gives rise to various catalytic applications such as the construction of membranes for syngas production by partial oxidation of methane. This article focuses on the Gd-doped cerium dioxides, which can be modified with Pt or Pd to enhance the reactivity of the lattice oxygen in interaction with methane. The aim of the work is the elucidation of correlations between the structural, electronic, and chemical properties of these nanomaterials. Detailed studies were performed for a series of samples with and without surface modification by noble metals using a complex combination of physicochemical methods: XRD, TEM, CH(4) TPR, XPS, SIMS, and FTIR spectroscopy of adsorbed CO. XPS and TPR data revealed that surface modification with noble metals enhances the reducibility of the doped ceria support, where the effect is more pronounced for Pd than for Pt. The formation of highly cationic Pd species due to strong metal support interactions provides a possible explanation for this behavior. Furthermore, the results obtained in the present work for the Gd-doped ceria system are compared to those obtained previously for the Pr-doped ceria system.     

Spectral Properties of the Periodic Magnetic Schrödinger Operator in the High-Energy Region. Two-Dimensional Case

The goal is to investigate spectral properties of the operator H=(–i +a(x))²+a₀(x) in the two-dimensional situation, a(x), a₀(x)) being periodic. We construct asymptotic formulae for Bloch eigenvalues and eigenfunctions in the high-energy region, describe properties of isoenergetic curves in the space of quasimomenta and give a new proof of the Bethe-Sommerfeld conjecture.Research partially supported by USNSF Grant DMS-0201383.Acknowledgements The author is thankful to Konstantin Makarov for very useful discussions and to Young-Ran Lee for her great help with pictures.     

Electrical properties of solid electrolytes with the general formula ABCD3 (A = Ag, Cu; B = Pb, Sn; C = As, Sb; and D = S, Se)

The electrical properties of AgPbSbS₃, AgSnAsS₃, AgPbSbSe₃, AgPbAsSe₃, AgSnSbSe₃, CuSnSbS₃, CuSnSbSe₃, CuSnAsSe₃, AgSnSbS₃, and AgPbAsS₃ chalcogenides are studied by the method of impedance spectroscopy with the aim of searching for materials with improved properties (increased contribution of ionic transport, decreased temperatures of onset of ionic transport, increased conductivity, the presence of ferroelectric and magnetic properties, etc.). New ionic conductors and ferroelectric semiconductors are discovered. Original Russian Text ? O.L. Kheifets, L.Ya. Kobelev, N.V. Melnikova, L.L. Nugaeva, 2007, published in Zhurnal Tekhnicheskoĭ Fiziki, 2007, Vol. 77, No. 1, pp. 90–96.