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1.
2.
V. M. Gun’ko 《Theoretical and Experimental Chemistry》2007,43(3):139-183
A review is presented on the multicomponent competitive adsorption, static equilibrium adsorption, and dynamic nonequilibrium
adsorption from gaseous and liquid media onto the surface of porous and disperse solids. The state of the theory of multicomponent
adsorption is analyzed. Not only traditional methods were used for investigations in this field but also NMR spectroscopy
(difference in the spectra of adsorbed and free compounds), FTIR spectroscopy (difference in the spectra of surface groups
and bonds in adsorbates), calorimetry, thermally stimulated depolarization, photon correlation spectroscopy, electrophoresis,
and cryoporometry.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 3, pp. 133–169, May–June, 2007. 相似文献
3.
Ashok K. Ganguli Shikha Nangia Meganathan Thirumal Pratibha L. Gai 《Journal of Chemical Sciences》2006,118(1):37-42
Using molten salt route (with NaCl/KCl as the salt) we have been able to synthesize a new form of magnesium tantalate at 850°C.
Powder X-ray diffraction data could be indexed on an orthorhombic unit cell with lattice parameters, ‘a’ = 15.36(1) ?, ‘b’ = 13.38(1) ? and ‘c’ = 12.10(1) ?. High resolution transmission electron microscopy and electron diffraction studies confirm the results obtained
by X-ray studies. Energy dispersive X-ray spectroscopy helps ascertain the composition of MgTa2O6. The title compound shows a dielectric constant of ∼24 with a low dielectric loss of 0.006 at 100 kHz at room temperature.
Dielectric constant is nearly unchanged with rise in temperature while the loss shows a very marginal increase (0.007 at 300°C).
Dedicated to Prof J Gopalakrishnan on his 62nd birthday. 相似文献
4.
M. Costa E Silva C. I. C. Galhano A. M. G. Moreira Da Silva 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):121-124
A monoterpene, D-carvone or (4S)-(+)-carvone, present in the essential oil of caraway seeds (Carum carvi L.), acts as a sprouting inhibitor agent for potato tubers in storage. The aim of the present study was to investigate the
possibility of using carvone/β-cyclodextrin inclusion compound as a sprout inhibitor agent for potato tubers. A Raman study
of the interactions between β-cyclodextrin (β-CD) and included carvone molecule in solid state is also reported; the results
confirm the synthesis of inclusion compound at pilot scale level. 相似文献
5.
Christopher F. Blanford Fraser A. Armstrong 《Journal of Solid State Electrochemistry》2006,10(10):826-832
We have conducted a series of experiments to explore the surface of the polished pyrolytic graphite ‘edge’ electrode as routinely prepared for use in protein film voltammetry. Our investigations have included nitrogen porosimetry and scanning electron microscopy. The nitrogen adsorption revealed a Brunauer–Emmett–Teller surface area ∼104 times greater than the geometric surface area of the electrode. The pore-size distribution calculated by the Horváth–Kawazoe method showed that 10–18% of the pore volume arises from pores having widths >10 nm and, thus, should be accessible to enzymes, although much of the exposed ‘wall’ surface may be inactive for enzyme binding or electron transfer: for example, it may be mainly basal plane. Scanning electron micrographs of the abraded pyrolytic graphite edge showed differing scales of surface damage caused by the abrasion and the presence of many cracks in the surface where thin platelets had been removed.This work is dedicated to Prof. Alan Bond on the occasion of his 60th birthday. Alan’s enthusiasm for the complexities of diffusion control persuaded one of us (F.A. Armstrong) to try and avoid it altogether in protein electrochemical studies. 相似文献
6.
G. I. Berezin G. A. Petukhova N. S. Polyakov M. L. Gubkina 《Russian Chemical Bulletin》1997,46(3):443-447
The state of water adsorbed on active carbons and canal soot was studied using the “chemical potential—entropy—temperature”
diagram. In the range of the relative pressures from 0.174 to 1, the state of adsorbed water is similar to the state of a
stretched liquid. The molar volume, heat of evaporation, and surface tension of stretched water were calculated at different
relative pressures. Near the spinodal, the molar volume of stretched water is 25% higher, and the surface tension is considerably
lower compared to water.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 464–468, March, 1997. 相似文献
7.
A new methodology for understanding the construction of polyhedral links has been developed on the basis of the Platonic solids
by using our method of the ‘n-branched curves and m-twisted double-lines covering’. There are five classes of platonic polyhedral links we can construct: the tetrahedral links;
the hexahedral links; the octahedral links; the dodecahedral links; the icosahedral links. The tetrahedral links, hexahedral
links, and dodecahedral links are, respectively, assembled by using the method of the ‘3-branched curves and m-twisted double-lines covering’, whereas the octahedral links and dodecahedral links are, respectively, made by using the
method of the ‘4-branched curves’ and ‘5-branched curves’, as well as ‘m-twisted double-lines covering’. Moreover, the analysis relating topological properties and link invariants is of considerable
importance. Link invariants are powerful tools to classify and measure the complexity of polyhedral catenanes. This study
provides further insight into the molecular design, as well as theoretical characterization, of the DNA polyhedral catenanes. 相似文献
8.
Sosale Chandrasekhar 《Research on Chemical Intermediates》1998,24(6):625-642
It is proposed that molecular phenomena may only be described within the framework of the Complementarity Principle (‘CP’),
and that scientific controversy may originate in the essential incompatibility of complementary representations. Complementarity
based on the temporal Uncertainty Principle leads to new insights into transition state theory, microscopic reversibility
and the Curtin-Hammett Principle. An empirical application of the ‘CP’ to the structural theory leads to a revision of present
concepts of ‘reaction dynamics’, with the Principle of Least Nuclear Motion (‘PLNM’) emerging as a general alternative to
electronic theories of reactivity. In fact, it is argued that the ‘PLNM’ is a better basis for the Woodward-Hoffmann rules
than is orbital symmetry. A more flexible approach to organic reaction mechanisms is thus indicated. Also, as the basis of
the structural theory is fundamentally uncertain, and the present theory of X-ray diffraction apparently incompatible with
the ‘UP’, a reinterpretation of the Bragg equation has been attempted. 相似文献
9.
D. M. Price 《Journal of Thermal Analysis and Calorimetry》1998,51(1):231-236
By employing a ‘modulated-temperature’ heating programme composed of a series of heat-isotherm stages, it is possible to separate
the change in dimensions of an oriented material during heating into two contributions: a thermally ‘reversing’ component
which is due to linear thermal expansion and a ‘non-reversing’ part arising from relaxation to the disordered state on heating
aboveT
g. Some preliminary results for biaxially drawn poly(ethylene terephthalate) film are presented.
These experiments were carried out at the Thermal Methods & Conservation Science Laboratory, Department of Chemistry, Birkbeck
College, University of London. 相似文献
10.
S Chandrasekhar 《Research on Chemical Intermediates》1997,23(1):55-62
By the temporal Uncertainty principle, chemical systems may be described in terms of ‘kinetic’ or ‘thermodynamic’ complementary
formulations, based on rate or equilibrium constants, and free energy changes respectively. Thereby, the paradox of the dichotomous
formulations of the Curtin-Hammett principle is resolved. A new formulation of the principle is suggested, and a fundamental
conflict with transition state theory is indicated. 相似文献
11.
Adsorption of a well-characterized cationic polyacrylamide (CPAM) onto the surface of a model colloid (monodisperse polystyrene
latex with carboxylic functional groups) was studied over a wide range of pH (4–9) and KCl concentration (c
s
=10-3–0.3 M). The surface charge density of the latex particles with and without adsorbed CPAM was also measured over the same
range of electrolyte compositions. The adsorbed amount of CPAM increases with increase in c
s
and pH. The polyelectrolyte adsorption alters substantially the surface charge density of the latex particles as compared
to the polymer-free case. A large overcompensation of the surface charge by the adsorbed polyelectrolyte is established at
high c
s
and low pH. A qualitative explanation of the observed features is put forward.
Received: 3 December 1996 Accepted: 20 January 1997 相似文献
12.
A biochemical fuel cell is a device which converts chemical energy into electrical power. The catalysts used in this process
can be either inorganic or organic type giving rise to ‘inorganic fuel cells’ or ‘biochemical fuel cells’, respectively. Biochemical
fuel cells use either micro-organism or enzymes as active components to carry out electrochemical reactions. The efficiency
of such a device theoretically can be as high as 90%. The difficulty in attaining these values arises due to sluggishness of electron transfer from active site to conducting electrode.
This can be overcome by using mediators or by immobilizing active components on conducting electrode. We have immobilizedfad-glucose oxidase on a graphite electrode using a semiconducting chain as a bridge. At the present stage of development, such
a device tacks high current densities, which is essential for commercial power generation but can be used in applications
such as pacemakers and glucose sensors. 相似文献
13.
L. K. Patrilyak I. A. Manza M. V. Okhrimenko 《Theoretical and Experimental Chemistry》2005,41(1):42-47
We have observed damped oscillations of increasing frequency in alkylation of benzene by 1-decene, which we interpret based on surface competition between the benzene and the coke being formed according to a mechanism of alternating inversions of the adsorption layer. We propose a scheme for the inversions in terms of chemical potentials of the adsorbed components. The change in the character of the oscillations is connected with a qualitative change in the coke over time.__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 40–44, January–February, 2005. 相似文献
14.
Rau María S. Gennero de Chialvo María Rosa Chialvo Abel C. 《Journal of Solid State Electrochemistry》2012,16(5):1893-1900
The carbon monoxide oxidation reaction (COOR) was studied on steady-state conditions by chronoamperometry on polycrystalline
smooth platinum and ruthenium rotating disc electrodes in CO-saturated acid solution. The chronoamperometric response did
not show current oscillations and therefore the current density (j) vs. overpotential (η) curves on steady state could be obtained. In order to interpret these results, kinetic expressions were derived starting
from the mechanism proposed by S. Gilman, which considers two adsorbed reaction intermediates, carbon monoxide (COad) and hydroxyl (OHad). Analytical expressions as a function of overpotential for the current density, the surface coverage of the adsorbed species
(θ
CO and θ
OH) and the CO and CO2 pressures at the electrode surface on steady state were obtained. This set of equations was used for the correlation of the
experimental polarization curves and the evaluation of the corresponding kinetic parameters. From these values, the dependences
of the surface coverage of the adsorbed intermediates on overpotential were simulated, as well as those of the partial pressure
of CO and CO2. Thus, it was demonstrated that the Gilman’s mechanism accurately describes the experimental results on steady state of the
COOR on these metals. 相似文献
15.
T. Z. Fahidy 《Russian Journal of Electrochemistry》2006,42(5):506-511
This paper summarizes experimental and theoretical investigations conducted by the author’s research group, prior to his official
retirement, on various aspects of electrochemically induced convective-flow and oscillatory instability and the stability
of electrochemical reactors.
Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 5, pp. 567–573.
The text was submitted by the author in English. 相似文献
16.
P. S. Fedotov M. S. Ermolin E. Yu. Savonina V. A. Kronrod B. Ya. Spivakov 《Journal of Analytical Chemistry》2010,65(12):1209-1214
A method for the continuous-flow fractionation of particles in a transverse centrifugal field in a rotating conoidal coiled
(RCC) column has been developed. A model of a planetary centrifuge with a conoidal drum of a special construction has been tested.
The effects of the rotation and revolution speed of the conoidal RCC, as well as the direction and pumping rate of the mobile
phase on the behavior of particles smaller than 1 μm have been studied. The conditions have been selected and optimized for
the retention and elution of spherical particles of the ‘150 nm’, ‘400 nm’, and ‘900 nm’ standard samples of silica gel (Polyscience Inc.). The possibility of using RCC for the analysis and production of monodisperse standard particle samples has been demonstrated.
In particular, the ‘900 nm’ particles have been separated from admixtures of small (100–200 nm) particles and nonspherical
1–2 μm particles present in the sample. The separated fractions have been characterized by electron microscopy. 相似文献
17.
Qiang Li Pingfan Wu Panchao Yin Jin Zhang Lu Shi Yongge Wei 《Journal of Cluster Science》2010,21(2):181-186
The α-octamolybdate-supported compound: [Fe(2,2′-bipy)3]2[α-Mo8O26] has been unexpectedly synthesized during a diffuse process and characterized by the IR spectroscopy, UV–Vis diffuse reflectance
spectroscopy and the single crystal X-ray diffraction. The title compound exhibits an interesting 3D honeycomb ‘host’ supramolecular
network with 1D channels, in which only α-octamolybdate anions ‘guests’ reside. The title compound shows the anisotropic property
and probably will be applied as a novel semiconductor in the future. 相似文献
18.
Similarities in properties among pairs of metallic elements and their compounds in the lower-right quadrant of the Periodic
Table have been named the ‘Knight’s Move’ relationship. Here, we have undertaken a systematic study of the only two ‘double-pairs’
of ‘Knight’s Move’ elements within this region: copper-indium/indium-bismuth and zinc-tin/tin-polonium, focussing on: metal
melting points; formulas and properties of compounds; and melting points of halides and chalcogenides. On the basis of these
comparisons, we conclude that the systematic evidence for ‘Knight’s Move’ relationships derives from similarities in formulas
and properties of matching pairs of compounds in the same oxidation state. Physical properties, such as melting points, do
not provide consistent patterns and trends and hence should not be considered as a common characteristic of this relationship. 相似文献
19.
P. Kluson M. Drobek A. Kalaji M. Karaskova J. Rakusan 《Research on Chemical Intermediates》2009,35(1):103-116
A series of phthalocyanines were prepared from phthalodinitrile and corresponding metal salts by means of the ‘solvent’ methods.
Some experiments were also conducted in the absence of a solvent in a ‘solvent-free’ process from phthalanhydride, urea and
metal chlorides. All of the prepared phthalocyanines were modified by the incorporation of desirable functional groups in
order to transform the virtually insoluble phthalocyanine skeleton into more soluble forms. Derivatives soluble in polar media
were prepared by means of sulphonation, while those soluble in non-polar media were produced by chlorosulphonation with the
subsequent condensation of prepared sulphochlorides with primary alkyl amines. 相似文献
20.
V. Yu. Borovkov S. P. Kolesnikov V. I. Koval’chuk J. L. d’Itri 《Russian Chemical Bulletin》2007,56(5):863-869
Adsorption of 13C18O+12C16O mixtures on the Pt(2.9%)/γ-Al2O3, (Pt(2.6%)+Cu(2.7%))/γ-Al2O3, and (Pt(2.6%)+Cu(5.1%))/γ-Al2O3 catalysts was studied by FTIR spectroscopy. On the metallic Pt surface at coverages close to saturation, CO is adsorbed both
strongly and weakly to form linear species for which the vibrational frequencies of the isolated 13C18O molecules adsorbed on Pt are ∼1940 and ∼1970 cm−1, respectively. The redistribution of intensities of the high-and low-frequency absorption bands in the spectra of adsorbed
13C18O indicates that these linear forms are present on the adjacent metal sites. The weak adsorption is responsible for the fast
isotope exchange between the gaseous CO and CO molecules adsorbed on metal. The Pt-Cu alloys, in which the electronic state
of the surface Pt atoms characteristic of monometallic Pt remains unchanged, are formed on the surface of the reduced Pt-Cu
bimetallic catalysts. The decrease in the vibrational frequencies of the isolated C=O bonds in the isolated Pt-CO complexes
suggests that the CO molecules adsorbed on the Cu atoms affect the electronic properties of Pt.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–836, May, 2007. 相似文献