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81.
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83.
The X-ray crystal structure of naphtho-9-crown-3 ether, 1 is reported. The molecule crystallizes in the monoclinic P2(1)/c space group with a=8.866(2) Å, b=6.451(1) Å, c=20.110(4) Å and β=91.055(4)°, with Z=4. The 2:1 naphtho-9-crown-3 LiClO4 complex, 2 crystallizes in the triclinic P-1 space group with a=10.5075(10) Å, b=11.7283(11) Å, c=15.9921(15) Å and β=84.289(2)°, with Z=2. There are two distinct complexes found in the crystal, one ordered and one disordered in the crown portion of the molecule. 13C CPMAS NMR spectra for 1 and 2 are presented. 相似文献
84.
Rheingold AL Liable-Sands LM Golen JA Yap GP Trofimenko S 《Dalton transactions (Cambridge, England : 2003)》2004,(4):598-604
The new ligand, hydrotris[3-(diphenylmethyl)pyrazol-1-yl]borate, Tp(CHPh2), has been synthesized and its coordination chemistry was compared with that of the analogous Tp(iPr). The new ligand was converted to a variety of complexes, such as M[Tp(CHPh2)]X (M = Co, Ni, Zn; X = Cl, NCO, NCS), Pd[Tp(CHPh2)][eta3-methallyl], Co[Tp(CHPh2)](acac), and Co[Tp(CHPh2)](scorpionate ligand). Compounds Tl[Tp(CHPh2)], 1, Co[Tp(CHPh2)]Cl, 2, Co[Tp(CHPh2)](NCS)(DMF), 3, Ni[Tp(CHPh2)](NCS)(DMF)2, 4, Co[Tp(CHPh2)](acac), 5, Co[Tp(CHPh2)][Ph2Bp], 6, Co[Tp(CHPh2)][Bp(Ph)], 7, Co[Tp(CHPh2)][Tp], 8, and (Ni[Tp(CHPh2)])2[C2O4](H2O)2, 9, were structurally characterized. 相似文献
85.
The potato-peeling problem asks for the largest convex polygon contained inside a given simple polygon. We give anO(n
7) time algorithm to this problem, answering a question of Goodman. We also give anO(n
6) time algorithm if the desired polygon is maximized with respect to perimeter.Work in this paper has been supported in part by NSF grants #DCR-84-01898 and #DCR-84-01633, the Office of Naval Research Grant N00014-82-K-0381, and by grants from Digital Equipment Corporation, the Sloan Foundation, the System Development Foundation, and the IBM Corporation. This paper contains the main results of the paper A Polynomial Solution for Potato-Peeling and other Polygon Inclusion and Enclosure Problems presented in the 25th Foundation of Computer Science Conference, 1984, Florida. The second half of that paper is submitted for publication elsewhere [1]. 相似文献
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88.
Yew Hoong Leong Sook Fwe Yap Khiok Seng Quek Eng Guan Tay Cherng Luen Tong Yao Teck Ong 《International Journal of Mathematical Education in Science & Technology》2013,44(8):1257-1267
In this article, we share our learning experience as a Lesson Study team. The Research Lesson was on Figural Patterns taught in Year 7. In addition to helping students learn the skills of the topic, we wanted them to develop a problem-solving disposition. The management of these two objectives was a challenge to us. From the lesson observation and the students’ classwork, it turned out better than we expected. 相似文献
89.
Li L Murthy NN Telser J Zakharov LN Yap GP Rheingold AL Karlin KD Rokita SE 《Inorganic chemistry》2006,45(18):7144-7159
A dinuclear copper(II) complex [Cu(II)2(PD'O-)(H2O)2](ClO4)3 (5) with terminal Cu(II)-H(2)O moieties and a Cu...Cu distance of 4.13 A (X-ray structure) has been synthesized and characterized by EPR spectroscopy (ferromagnetic coupling observed) and cyclic voltammetry. Dizinc(II) and mononuclear copper(II) analogues [Zn(II)2(PD'O-)(H2O)2]3+ (7) and [Cu(II)(mPD'OH)(H2O)]2+ (6), respectively, have also been synthesized and structurally characterized. Reacting 5/MPA/O(2) (MPA = 3-mercaptopropionic acid) with DNA leads to a highly specific oxidation of guanine (G) at a junction between single- and double-stranded DNA. Mass spectrometric analysis of the major products indicates a gain of +18 and +34 amu relative to initial DNA strands. The most efficient reaction requires G at the first and second unpaired positions of each strand extending from the junction. Less reaction is observed for analogous targets in which the G cluster is farther from the junction or contains less than four Gs. Consistent with our previous systems, the multinuclear copper center is required for selective reaction; mononuclear complex 6 is not effective. Hydrogen peroxide as a substitute for MPA/O2 also does not lead to activity. Structural analysis of a [Cu(II)2(PD'O-)(G)]3+ complex (8) and dizinc analogue [Zn(II)(2)(PD'O-)(G)](ClO4)3 (9) (G = guanosine) reveals coordination of the G O6 and N7 atoms with the two copper (or zinc) centers and suggests that copper-G coordination likely plays a role in recognition of the DNA target. The Cu2-O2 intermediate responsible for guanine oxidation appears to be different from that responsible for direct-strand scission induced by other multinuclear copper complexes; the likely course of reaction is discussed. 相似文献
90.
Wei Boon Yap Beng Ti Tey Noorjahan Banu Mohamed Alitheen Wen Siang Tan 《Journal of chromatography. A》2010,1217(21):3473-3480
Hepatitis B core antigen (HBcAg) is used as a diagnostic reagent for the detection of hepatitis B virus infection. In this study, immobilized metal affinity-expanded bed adsorption chromatography (IMA-EBAC) was employed to purify N-terminally His-tagged HBcAg from unclarified bacterial homogenate. Streamline Chelating was used as the adsorbent and the batch adsorption experiment showed that the optimal binding pH of His-tagged HBcAg was 8.0 with a binding capacity of 1.8 mg per ml of adsorbent. The optimal elution condition for the elution of His-tagged HBcAg from the adsorbent was at pH 7 in the presence of 500 mM imidazole and 1.5 M NaCl. The IMA-EBAC has successfully recovered 56% of His-tagged HBcAg from the unclarified E. coli homogenate with a purification factor of 3.64. Enzyme-linked immunosorbent assay (ELISA) showed that the antigenicity of the recovered His-tagged HBcAg was not affected throughout the IMA-EBAC purification process and electron microscopy revealed that the protein assembled into virus-like particles (VLP). 相似文献