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21.
Michael Grouchko Alexander Kamyshny Keren Ben-Ami Shlomo Magdassi 《Journal of nanoparticle research》2009,11(3):713-716
Synthesis of well dispersed copper nanoparticles was achieved by reduction of copper nitrate in aqueous solution using hydrazine
monohydrate as a reducer in the presence of preformed silver nanoparticles as catalysts. It has been demonstrated that addition
of silver nanoparticles to the reaction mixture leads to formation of aqueous dispersion of copper nanoparticles and also
results in a drastic reduction in reaction time compared to procedures reported in the literature. The absorption spectrum
of the dispersions, HR-TEM and STEM images and XRD pattern indicate the formation of copper nanoparticles with particle size
in the range of 5–50 nm. 相似文献
22.
Noelia Maldonado Vernica G. Vegas Oded Halevi Jose Ignacio Martínez Pooi See Lee Shlomo Magdassi Michael T. Wharmby Ana E. Platero‐Prats Consuelo Moreno Flix Zamora Pilar Amo‐Ochoa 《Advanced functional materials》2019,29(15)
This work presents the fabrication of 3D‐printed composite objects based on copper(II) 1D coordination polymer ( CP1 ) decorated with thymine along its chains with potential utility as an environmental humidity sensor and as a water sensor in organic solvents. This new composite object has a remarkable sensitivity, ranging from 0.3% to 4% of water in organic solvents. The sensing capacity is related to the structural transformation due to the loss of water molecules that CP1 undergoes with temperature or by solvent molecules' competition, which induces significant change in color simultaneously. The CP1 and 3D printed materials are stable in air over 1 year and also at biological pHs (5–7), therefore suggesting potential applications as robust colorimetric sensors. These results open the door to generate a family of new 3D printed materials based on the integration of multifunctional coordination polymers with organic polymers. 相似文献
23.
24.
For the displacement boundary value problem in nonlinear elastostatics with zero body force, an integral bound for the strain energy is obtained in terms of theL
2-norms of the given boundary displacements and their tangential derivatives (assumed sufficiently small). The constants involved depend upon the strain energy density function and upon the geometry of the domain. 相似文献
25.
26.
Reactions on tertiary hydrogen atoms, attached to unactivated saturated carbons, are very rare and usually inefficient. The electron density however, of a carbon-tertiary hydrogen bond is relatively high and therefore there is a chance it will react with a strong electrophile. One of the strongest electrophiles existing is, of course, the electrophilic fluorine. Two main sources for such an unusual species exist. One source is the various fluoroxy compounds like CF3OF or CF3COOF ant the other is the elemental fluorine itself.Indeed, when fluorine is allowed to react, at low temperatures, with various alkylcyclohexanol esters, a highly regio- and an absolutely stereospecific electrophilic substitution on the tertiary unactivated hydrogen takes place as for example: The radical pathway possibility of these reactions is excluded and it is believed that they are of ionic nature. By dehydrofluorination, a double bond is introduced in sites that no other reagent is known to do, thus activating the molecule towards further chemical transformations. The influence of the electron-withdrawing group on the reaction center will also be discussed.The described reaction is not restricted only to cyclic compounds as aliphatic chains also react as expected, i.e. The scope of these unusual reactions in both alicyclic and aliphatic fields will be evaluated. 相似文献
27.
28.
S. Shlomo 《Physics letters. [Part B]》1976,60(3):244-248
The contributions of the relativistic electromagnetic corrections to the Coulomb energy shifts are examined carefully in this note. In previous calculations, some of the terms were neglected or their contributions were not evaluated properly. In this note, we consider the appropriate expressions of the electromagnetic interactions and discuss their contributions to Coulomb energy shifts. 相似文献
29.
The discrimination between similar concentrations of the different metal ions is one of the important roles of fluorescent sensors. Here we present the study of the fluorescence dynamic of the chromophore bis-N-carbazolyl-distyrylbenzene (BCDSB) in acetonitrile/water (mmol/L), doped with metal ions such as K+; Ca++; Mg++; Zn++(10 micromol/L). BCDSB has the fluorescence with lambda(max) at 448 nm by excitation at lambda(exc) = 378 nm, lifetime 1.089 ns: quantum yield of the fluorescence is 0.68. With continuation of irradiation fluorescence quenching has been registered for all investigated metal ions. However, in the presence of Zn++ oscillation of the intensity was observed. The energy activation of the oscillation as much as 15 kcal/mol was estimated. We believe, that the specificity of the complex Zn++/BCDSB, is in an asymmetrical structure, formed via binding sites of Zn++ with the electron-enriched binding sites of the BCDSB, excited in n(pi)* state. This asymmetrical complex structure can cause the photoinduced structural fluctuation in the complex coordination. 相似文献
30.
We present an effective immunization strategy for computer networks and populations with broad and, in particular, scale-free degree distributions. The proposed strategy, acquaintance immunization, calls for the immunization of random acquaintances of random nodes (individuals). The strategy requires no knowledge of the node degrees or any other global knowledge, as do targeted immunization strategies. We study analytically the critical threshold for complete immunization. We also study the strategy with respect to the susceptible-infected-removed epidemiological model. We show that the immunization threshold is dramatically reduced with the suggested strategy, for all studied cases. 相似文献