A pulsed laser system is realized with graphene employed as a Q-switch.The graphene is exfoliated from its solution using an optical deposition and the optical tweezer effect.A fiber ferrule that already has the graphene deposited on it is inserted into an erbium-ytterbium laser(EYL)system with linear cavity configuration.We successfully demonstrate a pulsed EYL with a pulse duration of approximately 5.9μs and a repetition rate of 20.0 kHz. 相似文献
By conducting a structure-activity relationship study of the backbone of a series of oligoamide-foldamer-based α-helix mimetics of the Bak BH3 helix, we have identified especially potent inhibitors of Bcl-x(L). The most potent compound has a K(i) value of 94 nM in vitro, and single-digit micromolar IC(50) values against the proliferation of several Bcl-x(L)-overexpressing cancer cell lines. 相似文献
NiBr2 (DME) (DME = ethylene glycol dimethyl ether) reacts with 2-pyridinal-methyl-N-2,6-diisopropylphenylimine (L) in a 1:1 molar ratio in CH2Cl2 to give NiBr2(L) and [NiBrL2]Br · 4CH2Cl2 in 52% and 14% yield, respectively. The crystal of [NiBrL2]Br · 4CHCl3 obtained from CHCl3 was structurally characterized. 相似文献
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 .
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
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
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(n2) algorithm is presented, which is a substantial improvement over theO(n7) 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
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