共查询到20条相似文献,搜索用时 31 毫秒
1.
V. A. Kirsh 《Colloid Journal》2011,73(3):345-351
The calculation is implemented for the fiber collection efficiencies due to diffusion of nanoparticles in model filters, i.e.,
separate rows of fibers with an elliptic cross section located normal to the flow at different orientations of the ellipse
axes with respect to the flow. The Stokes flow field in the system of the fibers is found by the method of fundamental solutions.
The concentration field of Brownian particles and the efficiency of their deposition onto the fibers are determined from the
numerical solution of the equation for the convective diffusion. The dependence of the capture coefficient on the Peclet number
for elliptic fibers is shown to have the form η = APe−m, where exponent m changes from 2/3 to 3/4 at the parallel and normal orientation of the major axes of the ellipses with respect to the flow,
respectively. It is shown that, from the viewpoint of aerosol nanoparticle capture, the best filters are those in which the
fibers have a maximum midsection at the same cross-sectional area. 相似文献
2.
V. A. Kirsh 《Colloid Journal》2004,66(3):311-315
The diffusion deposition of submicron aerosol particles of a finite size on a model filter composed of parallel ultrafine fibers with a radius comparable with the mean free path of air molecules was considered. The diffusion capture coefficient with allowance made for particle interception
DR
is found by the numerical solution of the elliptic equation of steady-state convective diffusion in the wide ranges of interception parameter R, Peclet (Pe) and Knudsen (Kn) numbers at small Reynolds numbers. It was shown that, at small Kn numbers, the
DR
value exceeds the sum of capture coefficients due to specific deposition mechanisms, interception and diffusion, =
R
+
D
, whereas, at Kn > 1,
DR
. Within the range of intermediate Pe, Kn, and R numbers, the radius of the most penetrating particles is higher than the fiber radius. 相似文献
3.
The deposition of aerosol nanoparticles from Stokes flows in screen-type diffusion batteries designed for the determination
of diffusion coefficients for suspended nanoparticles is considered. Average fiber collection efficiencies η calculated for
screens consisting of two perpendicularly contacting rows of parallel equidistant straight fibers agree with the experimental
data obtained for woven screens within the Peclet number range Pe = 0.15−1000. It is shown that, for dense screens, the η
∼ Pe−2/3 power dependence is valid at Pe > 10. For rarefied screens, this dependence is fulfilled down to Pe ∼ 0.1. At Pe ≪ 1, the
integral flow of particles advancing on the fibers of the first row in the screen and the fiber collection efficiency, η of
an isolated row tends to a geometrical limit, which is equal to the ratio of the distance between the axes of the fibers to
the fiber diameter. 相似文献
4.
V. A. Kirsh 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(11):1949-1953
Diffusional particle deposition from a flow on fibers at low Reynolds number Re ≪ 1 is studied in a model filter consisting
of equidistant rows of parallel fibers perpendicular to the flow and forming a three-dimensional structure where one hexagonal
2D-dimensional lattice is inserted into another at the right angle. It is shown that under equal low filter packing density
fiber collection efficiencies calculated within 3D and 2D models are practically the same. 相似文献
5.
The electric constant (ɛ′) and dielectric loss (ɛ″) for dilute solutions of sulfolane in benzene solution has been measured
at 9.885 GHz at different temperatures (25, 30, 35, and 40°C) by using standard microwave techniques. Following the single
frequency concentration variational method, the dielectric relaxation time (τ) and dipole moment (μ) have been calculated.
It is found that dielectric relaxation process can be treated as the rate process, just like the viscous flow. Based on the
above studies, monomer structure of sulfolane in benzene has been inferred. The presence of solute-solvent associations in
benzene solution has been proposed. Energy parameters (ΔH
ɛ, ΔF
ɛ, ΔS
ɛ) for dielectric relaxation process of sulfolane in benzene at 25, 30, 35, and 40°C have been calculated and compared with
the corresponding energy parameters (ΔH
η, ΔF
η, ΔS
η) for the viscous flow. 相似文献
6.
Excess Molar Volume and Viscosity of Isobutyric Acid + Water Binary Mixtures Near and Far Away from the Critical Temperature 总被引:1,自引:0,他引:1
The excess molar volume VE, shear viscosity deviation Δη and excess Gibbs energy of activation ΔG∗E of viscous flow have been investigated by using density (ρ) and shear viscosity (η) measurements for isobutyric acid + water (IBA+W) mixtures over the entire range of mole fractions at five different temperatures,
both near and close to the critical temperature (2.055K ≤ (T−Tc)≤ 13.055K). The results were also fitted with the Redlich–Kister equation. This system exhibited very large negative values
of VE and very large positive values of Δη due to increased hydrogen bonding interactions and correlation length between unlike molecules in the critical region and
to very large differences between the molar volumes of the pure components at low temperatures. The activation parameters
ΔH∗ and ΔS∗ have been also calculated and show that the critical region has an important effect on the volumetric properties. 相似文献
7.
The difurylphosphido-bridged dinuclear complex [Ru2(CO)6(μ-PFu2)(μ-η1,η2-Fu)] (Fu = 2-furyl) 1 readily reacts with two equivalents of each of the terminal alkynes HC≡CR (R = Fc, p-C6H4Fc, p-C6H4NO2, Fc = Fe(η5-C5H5)(η5-C5H4)) by an interesting head-to-tail ynyl coupling with a furan group to form a series of phosphido-bridged diruthenium compounds
containing a novel furyl-substituted C4 hydrocarbyl chain of stoichiometry [Ru2(CO)4(μ-PFu2){μ-η1,η1,η2,η3-RCC(H)C(R)C(H)Fu}] (R = Fc 2, p-C6H4Fc 3, p-C6H4NO2
4) in moderate to good yields. Reaction of 1 with an equimolar amount of HC≡CFc and HC≡C(p-C6H4NO2) afforded a pair of isomers of [Ru2(CO)4(μ-PFu2){μ-η1,η1,η2,η3-R1CC(H)C(R2)C(H)Fu}] (R1 = Fc, R2 = p-C6H4NO2
5a; R1 = p-C6H4NO2, R2 = Fc 5b) together with a small mixture of 4. X-ray crystal structures of 2, 3, 5a and 5b are reported. All of these new alkyne-derived dinuclear complexes are electron precise with 34 cluster valence electrons
in which the μ-η1,η2-furyl ligand acts as a three-electron donor and the μ-phosphido Ru2 framework is retained in the products upon alkyne coupling reactions. The resulting organic fragment of each complex is coordinated
to the Ru atoms via a π, a π-allyl and two σ bonds, and donates seven electrons to the metal core.
Dedicated to the memory of Professor F. Albert Cotton. 相似文献
8.
V. A. Kirsh 《Colloid Journal》2007,69(5):615-619
The diffusion deposition of submicron aerosol particles in model filters consisting of fibers covered with permeable porous shells is studied. An ordered system of parallel cylinders arranged perpendicular to the flow is used as a model filter. The results of calculations are given for the dependences of the capture coefficient on the shell radius, the shell permeability, the packing density of the filters, the particle radius, and the flow velocity. Calculations are performed within a wide range of Peclet numbers. It is shown that the capture coefficient and the quality criterion γ of a filter increase with the diffusion mobility of particles and shell permeability, as well as that the dependence of the quality criterion on the radius of permeable shells has a maximum. It is also shown that the capture coefficients for fibers with porous shells, calculated using the cell model and the isolated row of fibers, almost coincide with one another. 相似文献
9.
The reactions of the Me
n
C6H6−n
M(CO)3 (M=Cr, Mo, W;n=3, 5, 6) and C5R5M(CO)3 (M=Mn, Re; R=H, Me) complexes with propargyl alcohol in acidic media under UV irradiation were studied. Novel Me
n
C6H6−n
M(CO)2(η3-C3H3)BF4 (M=Mo, W;n=3, 5, 6) and C5R5Re(CO)2(η3-C3H3)CF3SO3 complexes with the 3ē-propargyl ligand were synthesized, and their properties compared with those of similar η3-allyl derivatives. The structure and dynamic propeties of the compounds obtained are discussed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1796–1803, September, 1999. 相似文献
10.
Visible light irradiation of the [(η-C6H7)Fe(η-C6H6)]+ cation (1) in CH2Cl2 in the presence of alkyl-substituted benzenes results in arene exchange forming the [(η5-C6H7)Fe(η-C6R6)]+ cations (2a–d: C6R6 is toluene, p-xylene, mesitylene, and durene). The mixed bis(arene) [(η-C6H6)Fe(η-C6R6)]2+ iron complexes (3a–d) were synthesized by hydride ion abstraction from 2a–d by [Ph3C]+.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1864–1865, September, 2007. 相似文献
11.
The excess molar volumes, V
mE, viscosity deviations, Δη, and excess Gibbs energies of activation, ΔG
*E, of viscous flow have been investigated from density and viscosity measurements for two ternary mixtures, 1-butanol + triethylamine
+ cyclohexane and 1-pentanol + triethylamine + cyclohexane, and corresponding binaries at 303.15 K and atmospheric pressure
over the entire range of composition. The empirical equations due to Redlich-Kister, Kohler, Rastogi et al., Jacob-Fitzner,
Tsao-Smith, Lark et al., Heric-Brewer, and Singh et al. have been employed to correlate V
mE, Δη and ΔG
*E of the ternary mixtures with their corresponding binary parameters. The results are discussed in terms of the molecular interactions
between the components of the mixture. Further, the Extended Real Associated Solution, ERAS, model has been applied to V
mE for the present binary and ternary mixtures, and the results are compared with experimental data. 相似文献
12.
V. V. Vashchenko N. S. Pivnenko L. A. Kutulya A. S. Petrenko S. V. Iksanova J. W. Goodby 《Russian Chemical Bulletin》2000,49(7):1218-1230
1R,4R-2-(4-Phenylbenzylidene)-p-menthan-3-one in acidic media undergoes rearrangement with migration of the exocyclic double bond to the cyclohexane ring to form three 2-(4-phenylbenzyl) derivatives ofp-menthen-3-ones. The reaction products differ in the location of the endocyclic double bond (Δ1 or Δ4) and in the configuration of the new chiral C(2) center in the resultingp-menth-4-en-3-ones. The configurations of the 1R,2R- and 1R,2S-2-(4-phenylbenzyl)-p-menth-4-en-3-ones were established based on analysis of their1H NMR spectra in combination with calculations by molecular mechanics. The molecular conformations of these compounds as well as of some racemic 2-benzyl-p-menth-1-en-3-one derivatives were studied. 相似文献
13.
Shear viscosity deviations Δη have been investigated by using density (ρ) and kinematic viscosity (ν) measurements for isobutyric acid + water (IBA + W) mixtures over the entire range of mole fractions at atmospheric pressure
and at two temperatures (301.15 and 315.15 K). This study extends the temperature range from the five other temperatures investigated
in a previous work, 1.055 K≤(T−T
c
)≤14.055 K, both far from and close to the critical temperature. This system exhibits very large positive values of Δη due to increased hydrogen bonding interactions and the correlation length between unlike molecules in the critical region,
and to very large differences between the molar volumes of the pure components at low temperatures. The results were also
fitted with the Redlich–Kister polynomial equations and the recently proposed Herráez correlation equation. Comparisons between
the two models at different temperatures and number of parameters are discussed. We note that, in this system where the shear
viscosity η as a function of mole fraction (x
1) of IBA presents a maximum, experimental data are in agreement with the two correlation models when more than three parameters
are employed, especially for temperatures far from the critical temperature. 相似文献
14.
A. R. Kudinov D. A. Loginov P. V. Petrovskii M. I. Rybinskaya 《Russian Chemical Bulletin》1998,47(8):1583-1584
Thirty-electron triple-decker complexes with a central pentaphospholyl ligand [(η-C5Me5)Fe(μ-η:η-P5)M(η-C5R5)]BF4 (M=Fe, R=Me or M=Ru, R=H, Me) were synthesized by a stacking reaction of cationic 12-electron fragments [(η-C5R5)M]+ with (η-C5Me5)Fe(η-P5).
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1625–1626, August, 1998. 相似文献
15.
Miscibility of ethyl cellulose/copolyamide6/66/1010 blends by viscometry and refractive index method
Xiuzhen Zhang Yuhua Shen Anjian Xie Sulian Gao Zhiying Xing 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(4):617-620
The miscibility of ethyl cellulose (EC)/copolyamide6/66/1010 (PA-130) in formic acid is studied by viscometry and refractive
index techniques at 25°C. Using viscosity data, the criteria Δb, Δb′, Δ[η]m, interaction parameter μ, β and thermodynamic parameter α are calculated. These investigations indicate that blend of EC/PA-130
is miscible when the ethyl cellulose content is more than 50 wt % in the blend. Further the result was also confirmed by refractive
index measurements. 相似文献
16.
Abstract
Experimental densities ρ, viscosities η, and refractive indices n D of the ternary mixtures consisting of 2-methyltetrahydrofuran + chlorobenzene + cyclopentanone and constituted binary mixtures were measured at T = 298.15 K for the liquid region and at ambient pressure for the whole composition range. Excess molar volumes V\textm\textEV_{\text{m}}^{\text{E}}, deviations in the viscosity Δη, and deviations in the refractive index Δn D from the mole fraction average for the mixtures were derived from the experimental data. The excess partial molar volumes V\textm,i\textEV_{{\text{m}},i}^{\text{E}} were also calculated. The binary and ternary data of V\textm\textEV_{\text{m}}^{\text{E}}, Δη, and Δn D were correlated as a function of the mole fraction by using the Redlich–Kister and the Cibulka equations, respectively. McAllister’s three-body interaction model is used for correlating the kinematic viscosity of binary mixtures with the mole fraction. 相似文献17.
Densities (ρ) and viscosities (η) of different strengths of magnesium sulphate (MgSO4) in varying proportions of formamide (FA) + ethylene glycol as mixed solvents were measured at room temperature. The experimental
values of ρ and η were used to calculate the values of the apparent molar volume, (φ1,), partial molar volume, (φ1,ℴ) at infinite dilution,A- andB-coefficients of the Jones-Dole equation and free energies of activation of viscous flow, (Δμ
1
0*
) and (Δμ
2
0*
), per mole of solvent and solute respectively. The behaviour of these parameters suggests strong ion-solvent interactions
in these systems and also that MgSO4 acts as structure-maker in FA + ethylene glycol mixed solvents. 相似文献
18.
Ufuk Sancar Vural Fatih Durmaz Ozcan Kocyigit Hasan Kocyigit V. Muradoglu Beril Akin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(13):2260-2268
Excess molar volumes (V
E), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at
298.15 and 303.15 K. The excess molar volumes V
E were determined from density, while the excess Gibbs free energy of activation G*E was calculated from viscosity deviation Δη. The excess molar volume (V
E), viscosity deviation (Δη), and excess Gibbs energy of activation (G*E) were fitted to the Redlich-Kister polynomial equation to derive binary coefficients and estimate the standard deviations
between the experimental data and calculation results. All mixtures showed positive V
E values obviously caused by increased physical interactions between biodiesel and the organic solvents. 相似文献
19.
Paul Rademacher 《Structural chemistry》2006,17(1):19-25
The electronic and geometrical structures of fluorocyclopropanes (1–12) have been analysed using DFT B3LYP calculations. A linear relationship, Δɛω=−0.172 Δr−0.171 (n=12, R=0.931), between Δɛω (in eV), the difference of the energies of the Walsh orbitals ωS and ωA, and Δr (in pm), the difference of vicinal and distal C–C bond lengths, is established. Correcting the orbital splitting by the basic value at Δr=0.00 pm, an even better linear correlation Δɛω
eff=0.0720 Δr (n=12, R=0.984) is obtained. The results confirm the general applicability of the two-orbitals model for the relationship between geometrical and electronic structures for substituted cyclopropanes.
1For Part 4 see Ref. [17]. 相似文献
20.
Manapragada V. Rathnam Sharad Mankumare Kirti Jain M. S. S. Kumar 《Journal of solution chemistry》2012,41(3):475-490
Densities, viscosities and speeds of sound of binary mixtures of ethyl benzoate with cyclohexane, n-hexane, heptane and octane have been measured over the entire range of composition at (303.15, 308.15 and 313.15) K and at
atmospheric pressure. From these experimental values, excess molar volume (V
E), deviation in viscosity (Δη) and deviation in isentropic compressibility (ΔK
s) have been calculated. The viscosities of binary mixtures were calculated theoretically from the pure component data by using
various empirical and semi-empirical relations and the results compared with the experimental findings. 相似文献