CCl<Subscript>4</Subscript> Decomposition in RF Thermal Plasma in Inert and Oxidative Environments

The decomposition of carbon tetrachloride was investigated in an RF inductively coupled thermal plasma reactor in inert CCl₄–Ar and in oxidative CCl₄–O₂–Ar systems, respectively. The exhaust gases were analyzed by gas chromatography-mass spectrometry. The kinetics of CCl₄ decomposition at the experimental conditions was modeled in the temperature range of 300–7,000 K. The simulations predicted 67.0 and 97.9% net conversions of CCl₄ for CCl₄–Ar and for CCl₄–O₂–Ar, respectively. These values are close to the experimentally determined values of 60.6 and 92.5%. We concluded that in RF thermal plasma much less CCl₄ reconstructed in oxidative environment than in an oxygen-free mixture.     

Structural and thermal study of asymmetric α-dioxime complexes of Co(III) with Cl and methyl-pyridines

Two new cobalt(III)-chelates, trans-bis(methyl-ethyl-dioximato)-chloro-β-picoline-cobalt (III) (1), and trans-bis(methyl-ethyl-dioximato)-chloro-3,4-lutidine-cobalt (III) (2) were obtained by oxidizing a mixture of CoCl₂, methyl-ethyl-dioxime and amines: β-picoline (3-methyl-pyridine) for (1) and 3,4-lutidine (3,4-dimethyl-pyridine) for (2). The crystal structure of (1) was determined by single crystal XRD (monoclinic, space group P2₁/c (No. 14) with a = 8.391(3) Å, b = 14.421(5) Å, c = 18.383(8) Å, β = 114.57(2)°, R = 0.0499), while both (1) and (2) were studied by middle and far FTIR spectroscopy, electrospray ionization (ESI) MS, powder XRD and thermal analysis (TG/DTA-MS). Melting of the related complexes 1 and 2 at 219 and 184 °C, respectively, results in an immediate chemical degradation of their whole structure and tarring of ligands.     

Examination of the upper measurement limit in displacement measurement using fringe compensation in digital holography

Digital holography is a widely used method for displacement measurement in coherent optical metrology. An obvious limit of the method is that too large displacements result in dense fringes, so the fringes are practically invisible. The maximum number of contour fringes in displacement measurement is limited, because the cameras are discrete devices and sampling theory plays an important role. Because of the limited measurement range, compensation methods are promising tools for practical measurements. It can be shown that the practical measurement range can be extended above the Nyquist sampling limit. Compensation methods can be digital, because digital holographic interferometry operates with images recorded with a digital camera. In our research work the upper measurement range of fringe compensation method was examined. Our goal was to perform automatic compensation even if the displacement is higher than the measurement range of the basic method. The operation of the automatic fringe compensation method was based on the combination of two types of out-of-plane displacement measurements with different sensitivities.     

Partitioning 2-edge-colored graphs by monochromatic paths and cycles

We present results on partitioning the vertices of 2-edge-colored graphs into monochromatic paths and cycles. We prove asymptotically the two-color case of a conjecture of Sárközy: the vertex set of every 2-edge-colored graph can be partitioned into at most 2α(G) monochromatic cycles, where α(G) denotes the independence number of G. Another direction, emerged recently from a conjecture of Schelp, is to consider colorings of graphs with given minimum degree. We prove that apart from o(|V (G)|) vertices, the vertex set of any 2-edge-colored graph G with minimum degree at least \(\tfrac{{(1 + \varepsilon )3|V(G)|}} {4}\) can be covered by the vertices of two vertex disjoint monochromatic cycles of distinct colors. Finally, under the assumption that \(\bar G\) does not contain a fixed bipartite graph H, we show that in every 2-edge-coloring of G, |V (G)| ? c(H) vertices can be covered by two vertex disjoint paths of different colors, where c(H) is a constant depending only on H. In particular, we prove that c(C ₄)=1, which is best possible.     

Synthesis of vinca alkaloids and related compounds part 94. Epimerization of compounds with aspidospermane and D‐secoaspidospermane skeleton

The individual epimerization steps of vincadifformine ( 1 ), deethylvincadifformine isomers ( 2,3 ), their synthetic intermediates ( 4–13 ) as well as that of simpler compounds with D‐secoaspidospermane skeleton ( 15–17 ) were studied a ) in protic medium (boiling deuteroacetic acidic) and b ) under reductive (with sodium borodeuteride in boiling acetic acid, or with sodium borohydride in boiling deuteroacetic acid) conditions.     

Graph Pairs and their Entropies: Modularity Problems

Received June 24, 1997     

Birational rigidity of Fano varieties and field extensions

This note studies the behavior of birational rigidity and universal birational rigidity in extensions of algebraically closed fields.     

Nonlinear optimization with GAMS /LGO

The Lipschitz Global Optimizer (LGO) software integrates global and local scope search methods, to handle a very general class of nonlinear optimization models. Here we discuss the LGO implementation linked to the General Algebraic Modeling System (GAMS). First we review the key features and basic usage of the GAMS /LGO solver option, then present reproducible numerical results to illustrate its performance.