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LingLing Lv Sheng Yang XiaoFang Wang Kun Yuan XinWen Liu YongCheng Wang 《中国科学B辑(英文版)》2009,52(8):1176-1185
The potential energy surface crossings for 1,2-dithiete have been investigated using the complete active space self-consistent field(CASSCF) method and simple group theory.Using the full Pauli-Breit spin-orbit coupling(SOC) operator(■) SO) which consists of the one-electron(■) SO1) and two-electron(■) SO2) terms,we estimate the strengths of the SOC(198.37 cm-1 when symmetry is imposed,and 211.35 cm-1 with no symmetry constraints),which plays an essential role in the spin transitions between different spin s... 相似文献
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The mechanism of the Co(II) catalytic electroreduction of water insoluble CoR2 salt in the presence of cysteine was developed. CoR2 = cobalt(II) cyclohexylbutyrate is the component of a carbon paste electrode. Electrode surface consecutive reactions are:
(a) fast (equilibrium) reaction of the complex formation, (b) rate-determining reversible reaction of the promoting process of CoR(Ac+) complex formation, (c) rate-determining irreversible reaction of the electroactive complex formation with ligand-induced adsorption, and (d) fast irreversible reaction of the electroreduction. Reactions (a,b) connected with CoR2 dissolution and reactions (c,d) connected with CoR2 electroreduction are catalyzed by . Regeneration of (reactions “b,d”) and accumulation of atomic Co(0) (reaction “d”) take place. Experimental data [Sugawara et al., Bioelectrochem
Bioenergetics 26:469, 1991]: i
a vs E (i
a is anodic peak, E is cathodic accumulation potential), i
a vs , and i
a vs pH have been quantitatively explained. 相似文献
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Anil Kumar Nain 《Journal of solution chemistry》2007,36(4):497-516
The densities of binary mixtures of formamide (FA) with 1-butanol, 2-butanol, 1,3-butanediol, and 1,4-butanediol, including
those of the pure liquids, over the entire composition range were measured at temperatures (293.15, 298.15, 303.15, 308.15,
313.15 and 318.15) K and atmospheric pressure. From the experimental data, the excess molar volume, V
m
E, partial molar volumes, and , at infinite dilution, and excess partial molar volumes, and , at infinite dilution were calculated. The variation of these parameters with composition and temperature of the mixtures
are discussed in terms of molecular interactions in these mixtures. The partial molar expansivities, and , at infinite dilution and excess partial molar expansivities, and , at infinite dilution were also calculated. The V
m
E values were found to be positive for all the mixtures at each temperature studied, except for FA + 1-butanol which exhibits
a sigmoid trend wherein V
m
E values change sign from positive to negative as the concentration of FA in the mixture is increased. The V
m
E values for these mixtures follow the order: 1-butanol < 2-butanol < 1,3-butanediol < 1,4-butanediol. It is observed that
the V
m
E values depend upon the number and position of hydroxyl groups in these alkanol molecules. 相似文献
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Radosław Szmytkowski 《Journal of mathematical chemistry》2009,46(1):231-260
The derivative of the associated Legendre function of the first kind of integer degree with respect to its order, , is studied. After deriving and investigating general formulas for μ arbitrary complex, a detailed discussion of , where m is a non-negative integer, is carried out. The results are applied to obtain several explicit expressions for the associated
Legendre function of the second kind of integer degree and order, . In particular, we arrive at formulas which generalize to the case of (0 ≤ m ≤ n) the well-known Christoffel’s representation of the Legendre function of the second kind, Q
n
(z). The derivatives and , all with m > n, are also evaluated. 相似文献
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Mingqi Ao Peipei Huang Guiying Xu Xiaodeng Yang Yajing Wang 《Colloid and polymer science》2009,287(4):395-402
The aggregation behavior and thermodynamic properties of micellization for the ionic liquid-type gemini imidazolium surfactants
with different spacer length ([C12–s–C12im]Br2, s = 2, 4, 6) have been investigated by means of surface tension, electrical conductivity, dynamic light scattering and fluorescence
measurements. The values of cmc, γ
cmc, Γ
max, A
min, π
cmc, pc20 and cmc/pc20 suggest that the shorter the spacer, the higher the surface activity of [C12–s–C12im]Br2 is. The cmc and γ
cmc values are decreased significantly in the presence of sodium halides, and the values decrease in the order NaCl < NaBr < NaI.
The thermodynamic parameters of micellization (, , ) indicate that the micellization of [C12–2–C12im]Br2 and [C12–4–C12im]Br2 is entropy-driven, whereas aggregation of [C12–6–C12im]Br2 is enthalpy-driven at lower temperature but entropy-driven at higher temperature. Finally, the fluorescence measurements
show that the micropolarity of micelles increases but the aggregation numbers decrease with increasing the spacer length of
[C12–s–C12im]Br2. 相似文献
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H. Taşeli 《Journal of mathematical chemistry》2008,43(1):237-251
Special values of monic polynomials y
n
(s), with leading coefficients of unity, satisfying the equation of hypergeometric type
have been examined in its full generality by means of a unified approach, where σ(s) and τ(s) are at most quadratic and a linear polynomial in the complex variable s, respectively, both independent of n. It is shown, without actually determining the polynomials y
n
(s), that the use of particular solutions of a second order difference equation related to the derivatives y
n
(m)(z) is sufficient to deduce special values for some appropriate s = z points. Hence the special values of almost all polynomials and their derivatives can be generated by the universal formula
in which and are the discriminant and the roots of σ(s), respectively, and denote a parameter depending on the coefficients of the differential equation. Furthermore, the interrelations that arise
between and are also introduced. Finally, special values corresponding to the limiting and exceptional cases have been presented explicitly
for completeness.
相似文献
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Solubility of Oxygen in Some 1-1, 2-1, 1-2, and 2-2 Electrolytes as a Function of Concentration at 25°C 总被引:1,自引:0,他引:1
The solubility of oxygen has been measured in a number of electrolytes [(LiCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, NaNO3, KBr, KI, KNO3, CaCl2, SrCl2, BaCl2, Li2SO4, K2SO4, Mn(NO3)3)] as a function of concentration at 25°C. The solubilities, mol (kg-H2O)–1, have been fitted to a function of the molality m (standard deviation < 3mol-kg–1)
where A and B are adjustable parameters and the activity coefficient of oxygen )O2) = [O2]0/[O2]. The limiting salting coefficient, k
S = (ln / m)m=0 = A, was determined for all salts. The salting coefficients for the chlorides and sodium salts showed a near linear correlation with the crystal molar volume V
cryst = 2.52 r
3. The salting coefficients determined from the Scaled Particle Theory were in reasonable agreement with the measured values. The activity coefficients of oxygen in the solutions have been interpreted using the Pitzer equation
where
is a parameter that accounts for the interaction of O2 with cations (c) and anions (a) with molalities m
a and m
c, and
accounts for interactions for O2 with the cation and anion pair (c-a). The
and
coefficients determined for the most of the ions are in reasonable agreement with the tabulations of Clegg and Brimblecombe. The values of
for most of the ions are a linear function of the electrostriction molar volume (Velect = V0 – V
cryst). 相似文献
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Zhang Shimin 《Journal of mathematical chemistry》2006,39(2):441-450
To increase inert substance i will make the equilibrium translation rate α
j
of reactant j decrease if ∑
i
ν
i
< 0 or increase if ∑
i
ν
i
> 0. When
or
, to increase non-inert substance i will make α
j
increase if i is reactant (i ≠ j) or decrease if i is resultant. When
has maximum if i is reactant (i≠ j) or minimum if i is resultant. If i is reactant,
(x
r
0 is “optimum proportion” of reactant) 相似文献
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François Quentel Valentin Mirčeski Maurice L’Her 《Journal of Solid State Electrochemistry》2008,12(1):31-39
Thermodynamics and kinetics of hydrophilic ion transfers across water|n-octanol (W|OCT) interface have been electrochemically studied by means of novel three-phase and thin-film electrodes. Three-phase
electrodes used for thermodynamics measurements comprise edge plane pyrolytic graphite, the surface of which was partly modified
with an ultrathin film of OCT, containing hydrophobic lutetium bis(tetra-tert-butylphthalocyaninato) (Lu[tBu4Pc]2) as a redox probe. The transfers of anions and cations from W to OCT were electrochemically driven by reversible redox transformations
of Lu[tBu4Pc]2 to chemically stable lipophilic monovalent cation and anion , respectively. Upon reduction of Lu[tBu4Pc]2, the transfers of alkali metal cations from W to OCT have been studied for the first time, enabling estimation of their Gibbs
transfer energies. For kinetic measurements, a thin-film electrode configuration has been used, consisting of the same electrode
covered completely with a thin layer of OCT that contained the redox probe and a suitable electrolyte. Combining the fast
and sensitive square-wave voltammetry with thin-film electrodes, the kinetics of , , and Cl− transfers have been estimated.
Dedicated to Professor Dr. Yakov I. Tur’yan on the occasion of his 85th birthday. 相似文献
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Let G be a graph and d
v
denote the degree of the vertex v in G. The zeroth-order general Randić index of a graph is defined as where α is an arbitrary real number. In this paper, we investigate the zeroth-order general Randić index of conjugated unicyclic graphs G (i.e., unicyclic graphs with a perfect matching) and sharp lower and upper bounds are obtained for depending on α in different intervals. 相似文献
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Radosław Szmytkowski 《Journal of mathematical chemistry》2007,42(3):397-413
We present a comprehensive table of recurrence and differential relations obeyed by spin one-half spherical spinors (spinor
spherical harmonics) Ωκ μ(n) used in relativistic atomic, molecular, and solid state physics, as well as in relativistic quantum chemistry. First, we
list finite expansions in the spherical spinor basis of the expressions A·B Ωκμ(n) and A·(B×C) Ωκμ(n), where A, B, and C are either of the following vectors or vector operators: n=r/r (the radial unit vector), e
0, e
±1 (the spherical, or cyclic, versors), (the 2×2 Pauli matrix vector), (the dimensionless orbital angular momentum operator; I is the 2×2 unit matrix), (the dimensionless total angular momentum operator). Then, we list finite expansions in the spherical spinor basis of the
expressions A·B F(r)Ωκμ(n) and A·(B×C) F(r)Ωκμ(n), where at least one of the objects A, B, C is the nabla operator , while the remaining ones are chosen from the set . 相似文献
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Let λ1 (G) and Δ (G), respectively, denote the largest eigenvalue and the maximum degree of a graph G. Let
be the set of trees with perfect matchings on 2m vertices, and
. Among the trees in
, we characterize the tree which alone minimizes the largest eigenvalue, as well as the tree which alone maximizes the largest
eigenvalue when
. Furthermore, it is proved that, for two trees T
1 and T
2 in
(m≥ 4), if
and Δ (T
1) > Δ (T
2), then λ1 (T
1) > λ1 (T
2). 相似文献
20.
S. K. Poznyak V. V. Kharton J. R. Frade A. A. Yaremchenko E. V. Tsipis S. O. Yakovlev I. P. Marozau 《Journal of Solid State Electrochemistry》2008,12(1):15-30
The behavior of dense ceramic anodes made of perovskite-type (x = 0.30–0.70; y = 0–0.05; z = 0–0.20) and K2NiF4-type (Me = Co, Cu; x = 0–0.20) indicates significant influence of metal hydroxide formation at the electrode surface on the oxygen evolution reaction
(OER) kinetics in alkaline solutions. The overpotential of cobaltite electrodes was found to decrease with time, while cyclic
voltammetry shows the appearance of redox peaks characteristic of Co(OH)2/CoOOH. This is accompanied with increasing effective capacitance estimated from the impedance spectroscopy data, because
of roughening of the ceramic surface. The steady-state polarization curves of in the OER range, including the Tafel slope, are very similar to those of model Co(OH)2–La(OH)3 composite films where the introduction of lanthanum hydroxide leads to decreasing electrochemical activity. La2NiO4-based anodes exhibit a low electrochemical performance and poor stability. The effects of oxygen nonstoichiometry of the
perovskite-related phases are rather negligible at high overpotentials but become significant when the polarization decreases,
a result of increasing role of oxygen intercalation processes. The maximum electrocatalytic activity to OER was observed for
A-site-deficient , where the lanthanum content is relatively low and the Co4+ concentration determined by thermogravimetric analysis is highest compared to other cobaltites. Applying microporous layers
made of template-synthesized nanocrystalline leads to an improved anode performance, although the effects of microstructure and thickness are modest, suggesting a narrow
electrochemical reaction zone. Further enhancement of the OER kinetics can be achieved by electrodeposition of cobalt hydroxide-
and nickel hydroxide-based films.
Dedicated to Professor Dr. Yakov I. Tur’yan on the occasion of his 85th birthday. 相似文献