共查询到20条相似文献,搜索用时 15 毫秒
1.
Guy Yardeni Israel Zilbermann Eric Maimon Haim Cohen Dan Meyerstein 《Research on Chemical Intermediates》2009,35(4):543-554
A new CeIII complex was synthesized by mixing the ligand “dioxocyclam” with CeIII ions at pH 8.0 and its redox properties were investigated.
相似文献
Dan Meyerstein (Corresponding author)Email: |
2.
Polystyrene/silica, polystyrene–butylacrylate/silica, silylated polystyrene/silica, and silylated polystyrene–butylacrylate/silica hybrid composites were synthesized by the sol–gel method in tetrahydrofuran using HCl as catalyst and tetraethylorthosilicate as the silica precursor. The polymers were characterized by fourier transform infrared (FTIR), nuclear magnetic resonance, and gel permeation chromatography. The sol–gel mixtures were cast on glass plates and dried in air at 30°C for 72 h. The composites were characterized by FTIR, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy analysis. Silica (12.8%) could be incorporated within the silylated polystyrene–butylacrylate matrix while retaining optical transparency. These composites showed better thermal stability and water resistance in comparison to the individual polymers.
相似文献
S. K DoluiEmail: |
3.
Hitoshi Shirase Yurie Miura Yutaka Fukuda 《Monatshefte für Chemie / Chemical Monthly》2009,140(7):807-814
Abstract Mixed-ligand NiII complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined
by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky
ligands on the coordination distances and spectral properties are discussed.
Graphical Abstract
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Yutaka FukudaEmail: |
4.
Yan Gao Sabrina Reischmann Johannes Huber Tobias Hanke Rudolf Bratschitsch Alfred Leitenstorfer Stefan Mecking 《Colloid and polymer science》2008,286(11):1329-1334
Single semiconductor quantum dots were embedded into polymer particles with diameters below 0.1 μm by an emulsion polymerization
procedure or via a secondary dispersion approach. The photoluminescence properties of the nanocrystals are retained upon encapsulation,
as demonstrated by fluorescence confocal microscopy.
相似文献
Stefan MeckingEmail: |
5.
René Dybkaer 《Accreditation and quality assurance》2007,12(12):661-663
Terminology within a small laboratory community can be informal without danger of misunderstanding, but communication with
a wider audience and not least in publications, needs unequivocal terms for defined concepts. As an example, the many meanings
of “concentration” are explored to present a systematic nomenclature, including a concept diagram.
相似文献
René Dybkaer |
6.
Ines García-Lodeiro A. Fernández-Jiménez M. Teresa Blanco Angel Palomo 《Journal of Sol-Gel Science and Technology》2008,45(1):63-72
The study explored the compatibility between the main product of Portland cement hydration and the main product of the alkali
activation of fly ash: C–S–H and N–A–S–H gels, respectively. Both gels were synthesized with laboratory reagents at different
pH values. Blends of the two were synthesized as well, using the sol–gel procedure. All the gels were characterized with Fourier
transform IR spectroscopy (FTIR). The gels synthesized with this procedure were shown to precipitate together with a silica-rich
gel. In addition, the pH level was found to play a determinant role in both C–S–H and N–A–S–H gel synthesis. The C–S–H gel
is the major phase formed at pH > 11 and N–A–S–H gel for pH > 12. The results relating to the joint synthesis of the two (C–S–H
and N–A–S–H) gels were not conclusive. Technique used for the characterization failed to differentiate between them in the
blended material.
相似文献
Ines García-LodeiroEmail: |
7.
Renat R. Nazmutdinov Michael D. Bronshtein Dmitrii V. Glukhov Tamara T. Zinkicheva 《Journal of Solid State Electrochemistry》2008,12(4):445-451
Solvent dynamics effects on the electroreduction of [PtCl3(H2O)]− at a mercury electrode are explored in the framework of Sumi–Marcus model using an efficient computational scheme. According
to results of density functional calculations, the second electron transfer step may be regarded as rate controlling. The
nonmonotonous influence of solvent viscosity on the reaction rate is predicted and explained in terms of the saddle point
avoidance. The results of model calculations are employed to interpret experimental data reported earlier in the literature.
相似文献
Renat R. NazmutdinovEmail: |
8.
Xavier Fuentes-Arderiu 《Accreditation and quality assurance》2006,11(12):640-643
Protometrology is a new term recently proposed to designate the science of observation. As any field of knowledge needs a
terminological system, in this article a system of terms and definitions on protometrology, with examples belonging to clinical
laboratory sciences, is presented. This terminological system starts with the definitions of the two primitive concepts “object”
and “property”.
相似文献
Xavier Fuentes-ArderiuEmail: |
9.
Ernesto Paparazzo 《Foundations of Chemistry》2008,10(1):63-75
This paper analyzes views of the Stoic philosopher Posidonius (1st century BC) in the light of modern Chemistry. I propose
that Posidonius’ account on “generation and destruction” bears noteworthy similarities to the scientific notions of chemical
elements, chemical species, nuclear reactions, and the law of conservation of mass. I find that his views compare favorably
also with our understanding of chemical change at solid surfaces. Provided his thought is correctly placed in the cultural
context of his day, I argue that Posidonius deserves a previously un-acknowledged consideration in the historical background
of modern Chemistry.
相似文献
Ernesto PaparazzoEmail: |
10.
A. J. Appleby 《Journal of Solid State Electrochemistry》2009,13(7):991-997
A critical discussion of dioxygen reduction kinetics using the Tafel (for the irreversible cathode process) and the Butler–Volmer
(anode process) rate equations has been used to evaluate the accuracy of “standard” modeling interpretations of experimental
cell potential current (E–I) plots. The potential–current curve for what is believed to be an optimized Nafion™-bonded fuel cell cathode was analyzed.
It appears to behave as a well-ordered diffusional system and shows high electrocatalyst utilization based on its electrocatalytic
and gas diffusion characteristics. The electrode appears to perform as expected, without any anomalous characteristics showing
any lower than expected electrocatalyst utilization. Any improvement in electrode performance, which is certainly desirable,
seems to demand an improved diffusional structure, barring any potential (although unlikely) change in electrochemical kinetic
characteristics.
相似文献
A. J. ApplebyEmail: |
11.
Titanium grade 2 (UNS R50400) and nickel-based alloy (UNS N10276) were electrochemically investigated to explore their corrosion
susceptibility in sour (H2S) environments typically found on atmospheric distillation units in crude oil refineries. Electrochemical impedance spectroscopy
(EIS) was used to attain the experimental results. Two individual solutions (0.05 mol/l HCl and 0.05 mol/l HCl + 500 ppm H2S) were utilized in the laboratory work to replicate major corrosive agents present in actual atmospheric distillation systems
for a characteristic heavy crude oil produced in Mexico. Metals were examined at pH 1.5, 4, 6, 8, and 10 values for the two
solutions to identify the effects of pH modification on corrosion processes. The results disclosed that each metal has dissimilar
corrosion susceptibility depending on the pH of the environment. Therefore, pH intervals for which every metal holds minimum
susceptibility were identified. In addition, the convenience of controlling the pH of streams within a definite interval (5.5–6.5)
is discussed and a few hints on decision-making to improve the operation of atmospheric distillation units are also explained.
相似文献
J. Marín-Cruz (Corresponding author)Email: |
12.
13.
Vaporization enthalpies for the isomeric diazines were discussed within the context of recent measurements and estimation
techniques. It is suggested that pyridazine shows enigmatic behavior.
相似文献
Joel F. Liebman (Corresponding author)Email: |
14.
Philip J. Stewart 《Foundations of Chemistry》2007,9(3):235-245
Mendeleev’s failure to represent the periodic system as a continuum may have hidden from him the space for the noble gases.
A spiral format might have revealed the significance of the wide gaps in atomic mass between his rows. Tables overemphasize
the division of the sequence into ‘periods’ and blocks. Not only do spirals express the continuity; in addition they are more
attractive visually. They also facilitate a new placing for hydrogen and the introduction of an ‘element of atomic number
zero’.
相似文献
Philip J. StewartEmail: |
15.
The molecular geometries, relative stabilities, binding energies, and dissociation energies of NaDyBr4 and its molecular ion are discussed. Both the bidentate and tridentate isomers are stable for the neutral species, while
only the bidentate form is stable for NaDyBr4
+.
相似文献
Magdolna Hargittai (Corresponding author)Email: |
16.
Daniela Aiello Luca Malfatti Tongjit Kidchob Rosario Aiello Flaviano Testa Iolinda Aiello Mauro Ghedini Massimo La Deda Tonino Martino Maria Casula Plinio Innocenzi 《Journal of Sol-Gel Science and Technology》2008,47(3):283-289
Highly fluorescent materials have been prepared by incorporation of a zinc complex in mesoporous silica thin films with ordered
pore structure. The zinc complex has been introduced into the mesoporous materials via impregnation in an ethanol solution.
The incorporation into the films has been monitored by UV–Vis, Fourier transform infrared spectroscopy and spectroscopic ellipsometry.
After 18 h of immersion in the doping solution the films showed strong blue emission, increase in the refractive index. Leaching
experiments performed by immersing the samples in ethanol or tetrahydrofuran have shown that the chromophore is retained in
the porous matrix.
相似文献
Plinio InnocenziEmail: |
17.
Hinne Hettema 《Foundations of Chemistry》2008,10(2):135-142
Michael Weisberg’s recent 2007 paper on the chemical bond makes the claim that the chemical notion of the covalent bond is
in trouble. This note casts doubts on that claim.
相似文献
Hinne HettemaEmail: |
18.
Measurements of practical salinity are based on conductivity measurements, which are traceable to the conductivity of a defined
KCl reference solution. The conductivity of this reference solution must be traceable to the SI in order to state a reliable
uncertainty for practical salinity measurements and to guarantee their comparability. Currently, the conductivity ratios from
various old standard seawater batches are compared instead. However this method is inadequate on a long time-scale, which
is important for oceanography studies, because it lacks a time-invariant reference. Therefore the equivalence of conductivity
measurements traceable to primary conductivity standards has been investigated in Euromet project 918. Several European metrology
institutes measured the conductivity of a 5 S/m KCl solution and the practical salinity of IAPSO standard seawater. The study
estimates relative standard uncertainties to be of the order of 10−4 to 10−3 for such measurements.
相似文献
Steffen SeitzEmail: |
19.
The emission spectra of a series of molybdenum(II) chloride clusters containing thiolate ligands, [Mo6(μ3-Cl)8(SR)6]2− (R = Et, Bu, Ph, Bn), have been recorded. These complexes all show a broad emission at ~700 nm after excitation at 337, 400
and 410 nm. Determination of the excited state lifetimes and quantum yields of these complexes in acetonitrile reveals that
(Bu4N)2[Mo6(μ3-Cl)8(SPh)6] displays the longest excited state lifetime of this series (26 μs at 296 K).
相似文献
Lisa F. SzczepuraEmail: |
20.
Vibronic interactions have received increasing attention in modern structural chemistry. Edward Teller played a pioneering
role in understanding and describing them during the “molecular physics” period of his scientific career. Very little is known
about the two scientists who contributed significantly to our knowledge about these effects and whose names have become associated
with Teller’s. This Editorial is devoted to Hermann Jahn and Rudolf Renner and attempts to lift them out of oblivion by paying
them tribute for their contributions.
相似文献
István Hargittai (Corresponding author)Email: |