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181.
In this study we describe the set-up of a new passive integrating system to measure simultaneously 222Rn, 222Rn progeny (218Po and 214Po) and 220Rn concentration indoors. It consists of four Makrofol-DE (polycarbonate) circular foils. Two are enclosed within two diffusion chambers—each one with a different filter membrane—to measure 222Rn and 222Rn+220Rn. The other two foils are kept in direct contact with air and are electrochemically etched at different conditions to obtain the 222Rn daughters. Theoretical sensitivities of each Makrofol-DE foil are calculated using Monte-Carlo technique. The calculations are performed taking into account: (1) the Bethe–Bloch's expression for the stopping power of heavy charged particles in a medium, (2) the properties and behaviour of 222Rn, 220Rn and their progeny in the open air and within the diffusion chamber and (3) the etching conditions used to visualise -particles tracks. 相似文献
182.
183.
Ring Contraction of 3‐Hydroxy‐3‐(trifluoromethyl)piperidines: Synthesis of 2‐Substituted 2‐(Trifluoromethyl)pyrrolidines 下载免费PDF全文
Alexandra Feraldi‐Xypolia Dr. Domingo Gomez Pardo Prof. Janine Cossy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):12876-12880
A ring contraction of 3‐hydroxy‐3‐(trifluoromethyl)piperidines was achieved via an aziridinium intermediate. This contraction facilitates the synthesis of a series of 2‐substituted 2‐(trifluoromethyl)pyrrolidines incorporating a quaternary center at the C2 position. 相似文献
184.
García Camilo Navarro Freddy Ruíz-León Domingo Beltrán Olimpo García Aguirre María Jesús 《Journal of Solid State Electrochemistry》2017,21(1):243-253
Journal of Solid State Electrochemistry - In this work, a cationic porphyrin, ascribed as [Ttolyl(P-(C6H5)3)4]4+, where Ttolyl = 5,10,15,20 tetrakistolylporphyrin, was... 相似文献
185.
María D. Acosta Julio Becerra Guerrero Domingo García Sun Kwang Kim Manuel Maestre 《Journal of Mathematical Analysis and Applications》2014
We characterize the Banach spaces Y for which certain subspaces of operators from L1(μ) into Y have the Bishop–Phelps–Bollobás property in terms of a geometric property of Y, namely AHSP. This characterization applies to the spaces of compact and weakly compact operators. New examples of Banach spaces Y with AHSP are provided. We also obtain that certain ideals of Asplund operators satisfy the Bishop–Phelps–Bollobás property. 相似文献
186.
Herein we present the synthesis and characterization of new phosphonate‐, bisphosphonate‐ and hydroxybisphosphonatebenzimidazole derivatives substituted at the N‐1 position and new regioisomers phosphonate‐, bisphosphonate‐, and hydroxybisphosphonatebenzotriazole derivatives substituted at N‐1 or N‐2 positions. The compounds were characterized by NMR and IR spectroscopies, and mass spectrometry (low and high resolution) allowing the assignment of their structure, including the identification of regioisomers. These new azole monomers will be precursors for a mesoporous silica host to produce novel membrane materials with high proton conductivity for intermediate temperature proton exchange membrane fuel cells. 相似文献
187.
A set of seven non-substituted tri-atom-components (TACs) participating in [3+2] cycloaddition (32CA) reactions has been studied using the reactivity indices defined within the conceptual DFT at the B3LYP/6-31G(d) level of theory. This series of TACs shows a zwitterionic structure and low reactivity towards ethylene. The general characteristic of these TACs is their high nucleophilic and a low electrophilic behaviour. Activation energies computed at the MPWB1K/6-311G(d) level in dichloromethane point to that non-substituted TACs react quickly toward dicyanoethylene showing their ability to react towards electron-deficient ethylenes. However, when the TACs are electrophilically activated by an appropriate substitution there seems to be insufficient activation to react toward electron-rich ethylenes. The electrophilic activation of the TAC moiety for nucleophilic attacks was only determined by the coordination with a Lewis acid. All 32CA reactions studied in this work presented high regioselectivity. The polar character of these 32CA reactions is associated with the global charge transfer found at the TS, which is in agreement with a zwitterionic-type (zw-type) mechanism. According to our results, the present theoretical study suggests that the substitution is required in both, TACs and the ethylene species, in order to experimentally perform these zw-type 32CA reactions under mild conditions. 相似文献
188.
189.
Preparation and Characterization of Electrodes Modified with Pyrrole Surfactant,Multiwalled Carbon Nanotubes and Metallophthalocyanines for the Electrochemical Detection of Thiols 下载免费PDF全文
Magdalena Rangel Argote Elizabeth Sánchez Guillén Ana Gabriela Gutiérrez Porras Oracio Serrano Torres Cyrille Richard José H. Zagal Fethi Bedioui Silvia Gutierrez Granados Sophie Griveau 《Electroanalysis》2014,26(3):507-512
Our aim was to prepare hybrid electrodes active towards the electrooxidation of thiols by the co‐immobilization of native carbon nanotubes (CNTs) and cobalt phthalocyanine (CoPc) from aqueous solutions. This strategy was adopted to avoid the oxidation of CNTs that can induce a modification of their exceptional properties. To do so, a hydrosoluble pyrrole surfactant was used to get homogeneous aqueous dispersions of CNTs and CoPc and to trap both materials on the electrode via the electropolymerization of the pyrrole surfactant. The hybrid electrodes exhibit a good electrocatalytic activity towards the oxidation of L ‐cysteine and glutathione. Their performances in terms of limit of detection (0.01 mM) are compatible with the detection of these thiols in biological samples. 相似文献
190.
A Theoretical Study of the Interaction of Hydrogen and Oxygen with Palladium or Gold Adsorbed on Pyridine‐Like Nitrogen‐Doped Graphene 下载免费PDF全文
Dr. Eduardo Rangel Dr. Luis Fernando Magana Dr. Luis Enrique Sansores 《Chemphyschem》2014,15(18):4042-4048
The interaction of H2 and O2 molecules in the presence of nitrogen‐doped graphene decorated with either a palladium or gold atom was investigated by using density functional theory. It was found that two hydrogen molecules were adsorbed on the palladium atom. The interaction of these adsorbed hydrogen molecules with two oxygen molecules generates two hydrogen peroxide molecules first through a Eley–Rideal mechanism and then through a Langmuir–Hinshelwood mechanism. The barrier energies for this reaction were small; therefore, we expect that this process may occur spontaneously at room temperature. In the case of gold, a single hydrogen molecule is adsorbed and dissociated on the metal atom. The interaction of the dissociated hydrogen molecule on the surface with one oxygen molecule generates a water molecule. The competitive adsorption between oxygen and hydrogen molecules slightly favors oxygen adsorption. 相似文献