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71.
Kirill M. Skupov Pooja R. Marella Michel Simard Glenn P. A. Yap Nathan Allen David Conner Brian L. Goodall Jerome P. Claverie 《Macromolecular rapid communications》2007,28(20):2033-2038
The reaction of 2‐[bis(2‐methoxy‐phenyl)phosphanyl]‐4‐methyl‐benzenesulfonic acid (a) and 2‐[bis(2′,6′‐dimethoxybiphenyl‐2‐yl)phosphanyl]benzenesulfonic acid (b) with dimethyl(N,N,N′,N′‐tetramethylethylenediamine)‐palladium(II) (PdMe2(TMEDA)) leads to the formation of TMEDA bridged palladium based polymerization catalysts ( 1a and 1b ). Upon reaction with pyridine, two mononuclear catalysts are formed ( 2a and 2b ). These catalysts are able to homopolymerize ethylene and also copolymerize ethylene with acrylates or with norbornenes. With ligand b , high molecular weight polymers are formed in high yields, but higher comonomer incorporations are obtained with ligand a .
72.
Dr. Ka-Chun Au-Yeung Dengmengfei Xiao Dr. Wei-Chih Shih Hsiu-Wen Yang Dr. Yuh-Sheng Wen Prof. Glenn P. A. Yap Dr. Wen-Ching Chen Prof. Lili Zhao Prof. Tiow-Gan Ong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17350-17355
The reaction of Pd(OAc)2 with free carbodicarbene (CDC) generates a Pd acetate trinuclear complex 1 via intramolecular C(sp3)−H bond activation at one of the CDC methyl side arms. The solid structure of 1 reveals the capability of CDC to facilitate a double dative bond with two palladium centers in geminal fashion. This is attributed to the chelating mode of CDC, which can frustrate π-conjugation within the CDC framework. Such effect maybe also amplified by ligand-ligand interaction. The formation of other gem-bimetallic Pd−Pd, Pd−Au, and Ni−Au provides further structural evidence for this proof-of-concept in selective installation. Structural analysis is supported by computational calculations based on state-of-the-art energy decomposition analysis (EDA) in conjunction with natural orbitals for chemical valence (NOCV) method. 相似文献
73.
Rosenfeld (1971) proved that the Total Colouring Conjecture holds for balanced complete r-partite graphs. Bermond (1974) determined the exact total chromatic number of every balanced complete r-partite graph. Rosenfeld's result had been generalized recently to complete r-partite graphs by Yap (1989). The main result of this paper is to prove that the total chromatic number of every complete r-partite graph G of odd order is Δ (G) + 1. This result gives a partial generalization of Bermond's theorem. 相似文献
74.
We give a combinatorial definition of the notion of a simple orthogonal polygon beingk-concave, wherek is a nonnegative integer. (A polygon is orthogonal if its edges are only horizontal or vertical.) Under this definition an orthogonal polygon which is 0-concave is convex, that is, it is a rectangle, and one that is 1-concave is orthoconvex in the usual sense, and vice versa. Then we consider the problem of computing an orthoconvex orthogonal polygon of maximal area contained in a simple orthogonal polygon. This is the orthogonal version of the potato peeling problem. AnO(n
2) algorithm is presented, which is a substantial improvement over theO(n
7) time algorithm for the general problem.The work of the first author was supported under a Natural Sciences and Engineering Research Council of Canada Grant No. A-5692 and the work of the second author was partially supported by NSF Grants Nos. DCR-84-01898 and DCR-84-01633. 相似文献
75.
Y. Zhuang Y. J. Lin Y. F. Yap J. C. Chai N. Mathew 《Journal of Dispersion Science and Technology》2018,39(5):744-753
This study focuses on an experimental investigation of asphaltene deposition in a vertical transparent microchannel. Heptane-induced asphaltene precipitation is utilized to precipitate dissolved asphaltene in crude oil into asphaltene particles at ambient temperature and standard atmospheric pressure. These asphaltene particles deposit gradually on the surface of microchannels. The key parameters that influence the mechanism of asphaltene deposition are the ratio of crude oil to n-heptane and experimental elapsed time. At a constant flowrate, the amount of asphaltene deposited on a transparent channel wall is quantified using a new flow visualization technique based on reflected light intensity and image analysis. Asphaltene precipitation and deposition strongly affect the reflected light intensity through the change of mixture color in the recorded images. Experimental results show that asphaltene deposition process follows three stages, (i) slow asphaltene particle deposition at the beginning of the experiment, (ii) a rapid and continuous deposition occurring after few hours and (iii) a slower deposition (decreasing deposition rate) at the end of the experimentation. The experimental results for different crude oil to n-heptane ratios illustrate that deposition increases with this ratio, i.e. increasing concentration of n-heptane. An empirical equation is developed to correlate the intensity of the light absorption to the thickness of the deposited asphaltene in a transparent microchannel. Non-uniform deposition along the longitudinal direction of the microchannel is characterized. Deposits decrease with increasing longitudinal distance from the inlet. This non-uniform deposition distribution is due to local mass transport limitations and asphaltene aggregation size effect. 相似文献
76.
77.
78.
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
79.
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
80.
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