Partitioning of pi-electrons in rings of polycyclic benzenoid hydrocarbons. 2.1. Catacondensed coronoids

Various types of coronoids are examined for finding the partitioning of pi-electrons in individual benzenoid rings of polycyclic aromatic hydrocarbons. A class of catacondensed coronoids, namely fibonacenes, has four pi-electrons in every ring. Most other catacondensed coronoids have more than one type of benzenoid ring, each type with a different partition, but the average per ring is always four pi-electrons. For the class of catacondensed coronoids that have an acenic hole, simple quadratic equations in terms of their number R of rings exist for the partitions of pi-electrons in the three possible ring types.     

The splitting of d-orbitals in less symmetrical molecules containing a cyclopentadienyl ligand

The splitting of d orbitals in an electrostatic field due to a cyclopentadienyl ring and four ligands arranged at the corners of a square is investigated. It is shown that, although the symmetry of the molecule is C _s, the effective symmetry for the d ¹ and d ² systems is G _4v. The linear combinations for the d ² system in C _1v symmetry are given and the matrix elements for the secular determinant are listed. The results may be applied to a discussion of the bonding in tricarbonyl--cyclopentadienylethyl-molybdenum, whose structure is related to the idealized model considered.

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Zusammenfassung Bei der Aufspaltung der d-ZustÄnde in einem elektrostatischen Feld, welches erstens von einem Cyclopentadienyl-Ring und zweitens von vier an den Ecken eines Quadrates angeordneten Liganden hervorgerufen wird, ist die effektive Symmetrie D _4v — trotz der C _s-Symmetrie des Moleküls. Für das d ²-System werden die Linearkombinationen der Slaterdeterminanten und die Elemente der Störmatrix angegeben. Das Ganze lÄ\t sich z. B. auf die Diskussion von Tricarbonyl--cyclopentadienylÄthylmolybdÄn anwenden, dessen Struktur der des behandelten Modells sehr Ähnlich ist.

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Résumé La décomposition des orbitales d dans le champ d'un groupe cyclopentadiényl et de quatre ligandes arrangés en carré est étudiée. Pour les systèmes d ¹ et d ², la symétrie effective est C _4v , celle de la molécule n'étant que C _s. Pour d ², on donne les combinaisons linéaires adapté à la symétrie C _4v , et la matrice des énergie perturbatrices. Les résultats s'appliquent à la discussion du cyclopentadiényl-éthyl-molybdène tricarbonyle dont la structure ressemble le modèle étudié.

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On leave from: Institut Rudjer Bokovi, Zagreb, Yugoslavia     

Maximum overlap hybridization in cyclopropane and some related molecules

The hybridization in cyclopropane, spiropentane, nortricyclene and 1,1 -dimethyl cyclopropane is calculated applying the criterion of maximum overlap. The s-p content in the general hybrids is found to be sensitive to changes in the interorbital angle _ij. The results give information about the strain associated with bent bonds and its delocalization. The application also allows calculations of skeletal angles, such as C₁ C₂ C₃ in nortricyclene, which determine the geometry of the molecule.

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Zusammenfassung Die Hybridisierung in Cyclopropan, Spiropentan, Nortricyclen und 1,1-Dimethylcyclopropan wird mittels des Kriteriums der maximalen Überlappung berechnet. Dabei findet man eine starke Abhängigkeit des s- (p-) Anteils von dem von den Orbitalen gebildeten Winkel _ij. Daraus lassen sich Aussagen über die Spannung in Systemen mit anomalen Bindungswinkeln gewinnen. Der C₁ C₂ C₃-Winkel in Nortricyclen wird bestimmt.

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Résumé Nous calculons l'hybridation dans cyclopropane, spiropentane, nortricycléne et 1,1-diméthyl-cyclopropane à l'aide du critère de recouvrement maximal. Le rapport s/p dans les hybrides est sensible aux angles _ij entre les orbitales. Les résultats donnent des informations sur la tension dans les liaisons courbées. On peut aussi calculer des angles de squelette, comme C₁ C₂ C₃ dans le nortricyclène.

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Academic year 1964/65 at: Department of Chemistry, University of Ottawa, Ottawa, Ont., Canada.     

New color correction method for multi-view video using disparity vector information

Color inconsistency is an urgent problem to be solved in free viewpoint television. In this letter, a new color correction method is proposed by using disparity vector information. At first, we separate foreground and background from the scene with a method of mean-removed disparity estimation. Then the correction parameters are estimated by adopting linear fitting for foreground and background regions, respectively. Next, with expectation-maximization algorithm, we integrate correction parameters of foreground and background to get the final corrected image. Finally, video tracking technique is performed to correct multi-view video. Experimental results show that the proposed method is quite effective.     

Very efficient search for nucleotide alignments

We describe a very efficient search for nucleotide alignments, which is analogous to the novel very efficient search for protein alignment. Just as it has been the case with the alignment of proteins, based on 20 × 20 adjacency matrices for amino acids, obtained from a superposition of labeled amino acids adjacency matrices for the proteins considered, one can construct labeled matrices of size 4 × 4, listing adjacencies of nucleotides in DNA sequence. The matrix elements correspond to 16 pairs of adjacent nucleotides. To obtain DNA alignments, one combines information in the corresponding matrices for a pair of DNA nucleotides. Matrices are obtained by insertion of the sequential labels for pairs of nucleotides in the corresponding cells of the 4 × 4 tables. When two such matrices are superimposed, one can identify all segments in two DNA sequences, which are shifted relative to one another by the same amount in either direction, without using trial‐and‐error displacements of the two sequences one relative to the other to find local nucleotide alignments. © 2012 Wiley Periodicals, Inc.     

Novel numerical and graphical representation of DNA sequences and proteins

We have introduced novel numerical and graphical representations of DNA, which offer a simple and unique characterization of DNA sequences. The numerical representation of a DNA sequence is given as a sequence of real numbers derived from a unique graphical representation of the standard genetic code. There is no loss of information on the primary structure of a DNA sequence associated with this numerical representation. The novel representations are illustrated with the coding sequences of the first exon of β-globin gene of half a dozen species in addition to human. The method can be extended to proteins as is exemplified by humanin, a 24-aa peptide that has recently been identified as a specific inhibitor of neuronal cell death induced by familial Alzheimer's disease mutant genes.     

Determination of quaternary ammonium compounds by potentiometric titration with an ionic surfactant electrode: single-laboratory validation

A potentiometric titration for determining the quaternary ammonium compounds (QAC) commonly found in antimicrobial products was validated by a single laboratory. Traditionally, QACs were determined by using a biphasic (chloroform and water) manual titration procedure. Because of safety considerations regarding chloroform, as well as the subjectivity of color indicator-based manual titration determinations, an automatic potentiometric titration procedure was tested with quaternary nitrogen product formulations. By using the Metrohm Titrando system coupled with an ionic surfactant electrode and an Ag/AgCl reference electrode, titrations were performed with various QAC-containing formulation products/matrixes; a standard sodium lauryl sulfate solution was used as the titrant. Results for the products tested are sufficiently reproducible and accurate for the purpose of regulatory product enforcement. The robustness of the method was measured by varying pH levels, as well as by comparing buffered versus unbuffered titration systems. A quantitation range of 1-1000 ppm quaternary nitrogen was established. Eight commercially available antimicrobial products covering a variety of matrixes were assayed; the results obtained were comparable to those obtained by the manual titration method. Recoveries of 94 to 104% were obtained for spiked samples.