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141.
Three molecules of 5-(bromoacetyl) salicylate ( 1 ) complexed to Fe(III) ion were crosslinked with poly(ethylenimine) (PEI) in DMSO by alkylation of amino groups of PEI with 1 , leading to the formation of Fe(Sal)3PEI, a water-soluble polymer. Several other derivatives including the immobilized form were also prepared. Examination of the values of log Kf for the PEI derivatives indicated that each Fe(III) binding site in Fe(Sal)3PEI contains three salicylate moieties. In addition, the log Kf revealed that the effective molarity (EM) of the salicylate groups contained in the Fe(III) binding site is ca. 1000M. The high EM value shows that the geometry of the coordination sphere is well conserved during the crosslinkage with PEI of 1 preassembled around Fe(III) ion. In view of the EM value and the pKa values of salicylic phenols in apo(Sal)3-PEI, the metal-free form, the three salicylate groups of each Fe(III) binding site appear to occupy proximal positions leading to effective cooperation in Fe(III) binding. Fast, strong, and selective binding of Fe(III) ion by the binding site comprising three salicylate moieties was demonstrated. In addition, rapid demetalation of the resulting complexes as well as chemical stability of the immobilized chelating agents built on PEI were achieved. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1197–1210, 1997  相似文献   
142.
Polymeric oxaaza macrocycles (PEI-OAM) are constructed on poly(ethylenimine) (PEI) by Ni(II)-template alkylation of PEI with diethyleneglycol ditosylate. The Kf values for Ni(II), Cu(II), and Zn(II) complexes of PEI–OAM are measured at pH 3.5–10 at 25°C. At pH 7, log Kf values for these complexes are 9–15, indicating that the polymeric oxaaza macrocycles can readily reduce concentrations of these metal ions below ppb level. Metal binding ability of nonpolymeric oxaaza macrocyclic compounds reported in the literature decreases rapidly as pH is lowered below 7, whereas that of PEI–OAM decreases to lesser extents. This is attributed to the electrostatic effects exerted by the ammonium ions of PEI backbone. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 527–532, 1997.  相似文献   
143.
Erbium doped LiNbO3 (Er:LiNbO3) single crystal fibers were grown free of cracks along c‐axis by the micro‐pulling down (μ‐PD) method. We have investigated the up‐conversion property with the change of doped Er2O3 concentration and the starting melt composition. An enhancement of green upconversion according host matrix is also observed the stoichiometric LiNbO3. And, the dependence of the green emission according to Er3+ concentration is analyzed. The possible application of the Er3+ doped stoichiometric LiNbO3 single crystal fiber for up‐conversion based optical devices is discussed.  相似文献   
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146.
A polymer–surfactant micellar complex has been studied as a fluorescence resonance energy transfer (FRET) donor to fluorescein‐labeled DNA (ssDNA‐Fl). In water, the molar absorptivity and fluorescence quantum efficiency of cationic poly(fluorene‐co‐phenylene) (c‐PFP) are substantially increased in the presence of non‐ionic surfactants. A TEM microscopic study shows the formation of a nanowire micellar complex of c‐PFP and the surfactants. About a 400% enhancement of the FRET signal is measured in c‐PFP/ssDNA‐Fl with Brij 30, relative to that without surfactants. The signal amplification is successfully modulated using different types of non‐ionic surfactants which perturb the complexation, fine‐structure of the complex (i.e., donor‐acceptor separation), and the resulting energy transfer process.

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147.
We report that poly(3,4‐ethylenedioxythiophene) derived from poly(ionic liquid) (PEDOT:PIL) constitutes a unique polymeric hole‐injecting material capable of improving device lifetime in organic light‐emitting diodes (OLEDs). Imidazolium‐based poly(ionic liquid)s were engineered to impart non‐acidic and non‐aqueous properties to PEDOT without compromising any other properties of PEDOT. A fluorescent OLED was fabricated using PEDOT:PIL as a hole‐injection layer and subjected to a performance evaluation test. In comparison with a control device using a conventional PEDOT‐based material, the device with PEDOT:PIL was found to achieve a significant improvement in terms of device lifetime. This improvement was attributed to a lower indium content in the PEDOT:PIL layer, which can be also interpreted as the effective protection characteristics of PEDOT:PIL for indium extraction from the electrodes.

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148.
Jung Ki Suh  Jin Bok Lee 《Talanta》2009,78(1):321-13
Reliable determination of arsine (AsH3) in gases is of great importance due to stringent regulations associated with health, safety and environmental issues. It is, however, challenging for an analyst to determine trace airborne arsine concentrations without specifically designed collection procedures using adsorption, desorption, dissolution or impinging techniques. To circumvent such technical barrier, we have newly developed a direct analytical method, characterized by introduction of an arsine gas sample into stable plasma stream, followed by gas-phase oxidation of arsine with molecular oxygen in a dynamic reaction cell (DRC) equipped within the inductively coupled plasma-mass spectrometry (ICP/MS) system, followed by subsequent detection of AsO+ ion. This preliminary work used trace arsine concentrations (161 μg m−3, 322 μg m−3, and 645 μg m−3) gravimetrically prepared in N2 balance. The proposed method was optimized for the important experimental parameters such as the flow rates of the reaction gas, the arsine sample, and the carrier gas. This method was then validated by demonstrating good figure-of-merits including the low limit of detection (0.10 μg m−3), good linearity (r2 > 0.9915), low measurement uncertainty (0.66%), and high speed of analysis (<6 min). The proposed method is expected to be potentially applicable to the determination of arsine in real workplace air after appropriate modifications are made.  相似文献   
149.
Quick on the uptake : Palladium nanoparticles were fabricated simply by immersing {[Zn3(ntb)2(EtOH)2]?4 EtOH}n ( 1 ) in an MeCN solution of Pd(NO3)2 at room temperature, without any extra reducing agent. 3 wt % PdNPs@[ 1 ]0.54+(NO3?)0.54 significantly increase H2 uptake capacities, both at 77 K and 1 bar and at 298 K and high pressures (see picture, red curve) compared to [Zn3(ntb)2]n (black). ntb=4,4′,4′′‐nitrilotrisbenzoate.

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150.
We give some non-existence theorems for Hopf real hypersurfaces in complex two-plane Grassmannians G 2(? m+2) with parallel structure Jacobi operator R ξ.  相似文献   
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