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101.
Hexa‐armed and thiophene (Thi) end‐capped poly(ε‐caprolactone) star polymer (N3P3‐(PCL‐Thi)6), containing cyclotriphosphazene core, was prepared in a four‐step reaction sequence. Ring‐opening polymerization (ROP) and “click chemistry” techniques were employed in the first and final steps, respectively. Hexa‐armed PCL star polymer (N3P3‐(PCL‐OH)6) was successfully synthesized via ROP of ε‐caprolactone (ε‐CL) by using hekzakis(p‐(hydroxymethyl)phenoxy) cyclotriphosphazene as the multisite initiator and tin(II) 2‐ethylhexanoate (Sn(Oct2)) as the catalyst in bulk at 115 °C. Further modifications of the N3P3‐(PCL‐OH)6 were accomplished by derivatization of the hydroxyl‐functional chain ends. The obtained N3P3‐(PCL‐OH)6 was then reacted with 2‐bromo‐2‐methylpropanoyl bromide, and this led to a star polymer with bromide end groups, N3P3‐(PCL‐Br)6. In the third step, N3P3‐(PCL‐Br)6 was azidified with sodium azide (NaN3) in DMF affording N3P3‐(PCL‐N3)6. Conversion of the azide chain end groups into Thi was quantitatively accomplished via the “click reaction” between N3P3‐(PCL‐N3)6 and prop‐2‐yn‐1‐yl 3‐thienyl acetate in the final step. Subsequently, the star polymer with six Thi chain ends (N3P3‐(PCL‐Thi)6) was employed in electrochemical copolymerization with both pyrrole and Thi. Electrochromic properties and electrochromic device application of N3P3‐(PCL‐Thi)6/PThi were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3668–3682, 2010  相似文献   
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In this paper we prove that a finite group G with Cohen-Macaulay mod p cohomology will have non-trivial undetectable elements in if and only if G is a p-group such that every element of order p in G is central. Applications and examples are also provided. Received: April 18, 1996  相似文献   
105.
An adapted-bubbles approach which is a modification of the residual-free bubbles (RFB) method, is proposed for the Helmholtz problem in 2D. A new two-level finite element method is introduced for the approximations of the bubble functions. Unlike the other equations such as the advection-diffusion equation, RFB method when applied to the Helmholtz equation, does not depend on another stabilized method to obtain approximations to the solutions of the sub-problems. Adapted-bubbles (AB) are obtained by a simple modification of the sub-problems. This modification increases the accuracy of the numerical solution impressively. We provide numerical experiments with the AB method up to $ch = 5$ where $c$ is the wavenumber and $h$ is the mesh size. Numerical tests show that the AB method is better by far than higher order methods available in the literature.  相似文献   
106.
1,3‐Bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane ( L ) complexes with Fe(NO3)3, CoCl2, Co(NO3)2, Ni(NO3)2, CuCl2, Cu(ClO4)2, PdCl2, CdI2, Hg(NO3)2 were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT‐IR, NMR, ESI‐MS, fluorescence spectroscopy. Also, the crystal structure of 1,3‐bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane]dichlorocobalt(II), [Co( L )Cl2], complex is reported that it has distorted trigonal bipyramidal geometry. Antibacterial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. The Hg(II) complex shows superior activity toward S. epidermidis and E. coli whereas the other complexes are ineffective except the Co(NO3)2 complex: it showed weak activity toward all of the microorganisms.  相似文献   
107.
In this article, the sub‐equation method is presented for finding the exact solutions of a nonlinear fractional partial differential equations. For this, the fractional complex transformation method has been used to convert fractional‐order partial differential equation to ordinary differential equation. The fractional derivatives are described in Jumarie's the modified Riemann–Liouville sense. We apply to this method for the nonlinear time fractional differential equations. With the aid of symbolic computation, a variety of exact solutions for them are obtained. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
108.
In the present work, a series of aminocyclotriphosphazene containing sulfur group compounds have been synthesised and characterised by elemental analysis, mass (MS), 1H and 31P NMR spectroscopies. The formation of thiophenoxy-substituted aminocyclotriphosphazenes could be explained by different mechanisms based on primary or secondary amino-substituted cyclotriphosphazenes. Compounds 3, 5 and 7 could be formed by a proton abstraction-chloride elimination and 9, 11 and 13 may be constituted both the SN2 and SN1 reaction mechanisms, respectively. These mechanisms are supported by the crystal structures of 5 and 13. Molecular and crystal structures of 5 and 13 have been characterised by X-ray crystallography. The structures of 5 and 13 are monoclinic and have space groups P21/n.  相似文献   
109.
We propose a generic model for the “weighted voting” aggregation step performed by several methods in supervised classification. Further, we construct an algorithm to enumerate the number of distinct aggregate classifiers that arise in this model. When there are only two classes in the classification problem, we show that a class of functions that arises from aggregate classifiers coincides with the class of self-dual positive threshold Boolean functions.  相似文献   
110.
Herein, we report the development of extremely sensitive sandwich assay of kanamycin using a combination of anti-kanamycin functionalized hybrid magnetic (Fe3O4) nanoparticles (MNPs) and 2-mercaptobenzothiazole labeled Au-core@Ag-shell nanoparticles as the recognition and surface-enhanced Raman scattering (SERS) substrate, respectively. The hybrid MNPs were first prepared via surface-mediated RAFT polymerization of N-acryloyl-l-glutamic acid in the presence of 2-(butylsulfanylcarbonylthiolsulfanyl) propionic acid-modified MNPs as a RAFT agent and then biofunctionalized with anti-kanamycin, which are both specific for kanamycin and can be collected via a simple magnet. After separating kanamycin from the sample matrix, they were sandwiched with the SERS substrate. According to our experimental results, the limit of detection (LOD) was determined to be 2 pg mL−1, this value being about 3–7 times more than sensitive than the LOD of previously reported results, which can be explained by the higher SERS activity of silver coated gold nanoparticles. The analysis time took less than 10 min, including washing and optical detection steps. Furthermore, the sandwich assay was evaluated for investigating the kanamycin specificity on neomycin, gentamycin and streptomycin and detecting kanamycin in artificially contaminated milk.  相似文献   
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