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1.
Densities and viscosities of glycine and l-valine have been measured at 308.15 and 318.15 K in aqueous tripotassium citrate solutions ranging from 0.2 to 0.8 mol kg− 1 of tripotassium citrate. The viscosity data have been analyzed by Jones-Dole equation. The activation parameters of viscous flow have been obtained to throw light on the mechanism of viscous flow. The values of apparent molar volume, partial molar volume at infinite dilution and relative viscosities of each amino acid in various aqueous tripotassium citrate solutions have been evaluated from the density and viscosity data. The partial molar volumes of transfer from water to aqueous tripotassium citrate solution at infinite dilution have also been calculated. Transfer volume data have been used to calculate the pair and triplet interactions. The results have been discussed in terms of solute-solute and solute-solvent interactions and the structural changes of the solutes in solutions.  相似文献   

2.
Preliminary results from the correlation femtoscopy of identical kaons in the SELEX experiment (Fermilab E781) are presented. Kaons are selected in inclusive reactions of Σ?C(Cu) interactions at an initial energy of 610 GeV. Kaon pairs are studied in all possible charged states: K s 0 K s 0 , K s 0 K+, K s 0 K?, K+K+, K+K? and K?K?. The source sizes of the hadronization region of neutral and charged kaon pairs are measured.  相似文献   

3.
Measurements of the change in heat (enthalpy) of solid-solid transition ΔHt and of fusion ΔHfus in crystalline CsCl effected by the presence of guest ion K+ up to 56.5 mol% using differential scanning calorimetry are reported. The range of K+ solubility is found to be higher and at variance with the subsolidus region described in earlier reports. Novel features of ΔHt and ΔHfus dependence on solute composition are in contrast to parallel binary systems, viz. CsNO3-RbNO3, CsNO3-TlNO3 and RbNO3-TlNO3. Some fundamental solution quantities are calculated from heat of transition, viz. slope ΔHt/x or and χ-apparent partial molar heat of solution and partial molar heat of solution at infinite dilution, respectively.  相似文献   

4.
Predictions for semi-leptonic decay rates of theτ lepton into two meson final statesK ?π0 v τ, $\overline {K^0 } \pi - v_\tau $ ,K 0 K ? v τ, and three meson final statesK ?π? K + v τ, $K^0 \pi ^ - \overline {K^0 } v_\tau $ ,K sπ? K s v τ,K sπ? K L v τ,K Lπ? K L v τ,K ?π0 K 0 v τ, π0π0 K ? v τ,K ?π?π+ v τ, π? K 0π0 v τ are derived. The hadronic matrix elements are expressed in terms of form factors, which can be predicted by chiral Lagrangians supplemented by informations about all possible low-lying resonances in the different channels. Isospin symmetry relations among the different final states are carefully taken into account. The calculated branching ratios are compared with measured decay rates where data are available.  相似文献   

5.
Physicochemical properties such as density (ρ), viscosity (η), ultrasonic speed (u) of ionic liquid tetrabutylphosphonium tetrafluoroborate in acetonitrile, tetrahydrofuran, 1,3-dioxolane, and their binaries have been studied over the entire range of composition at 298.15°K. Apparent molar volumes (? V ) and viscosity B-coefficients supplemented with the data of densities and viscosities, respectively, have been interpreted in terms of ion–solvent interactions. The limiting apparent molar volumes (? V 0 ), experimental slopes (S V ? ) derived from the Masson equation, and viscosity A and B-coefficients analyzed by the Jones–Dole equation have also been interpreted. The adiabatic compressibility (β) has been evaluated using the ultrasonic speed (u) values. Thereafter, limiting apparent molar adiabatic compressibilities (? K 0  ) have been evaluated and discussed for the same.
Figure
Novelty and main finding: The derived communications of an ionic liquid widespreading in significant solvents enable the researchers to focus on replacing VOSs by proper solvents for simple transformations with minimum chemical waste and environmental pollution.  相似文献   

6.
Densities and viscosities were measured for the binary dilute mixtures of triethylene glycol monomethyl ether (TRIEGMME) in 2-alcohols (2-propanol (2-PR), 2-butanol (2-BU), and 2-pentanol (2-PE)) and tetraethylene glycol dimethyl ether (TEGDME) in 2-pentanol, at temperatures from 288.15 K to 318.15 K and in 0 ≤ x2 ≤ 0.10 mol fraction range of the polyalkyl glycol ethers. The values of the dynamic viscosity in the TRIEGMME + 2-PR systems are more viscous than pure solvent at the work temperatures. The Jones-Dole B coefficients and βG interaction parameters for viscous flow values were calculated and explain the behavior observed. The partial molar volumes at infinite dilution of solute in 2-alkanols were calculated by the parameters of viscous flow obtained in dilute solutions polyalkyl glycol ethers in 2-alkanols. The values have been compared with the values of partial molar volume at infinite dilution obtained by density measurement for both solutes in the 2-propanol, 2-butanol, and 2-pentanol.  相似文献   

7.
Densities ρ, speeds of sound u, viscosities η and refractive indices nD of binary mixtures of octan-2-ol with benzene, chlorobenzene and bromobenzene have been measured over the entire range of composition at 298.15 and 303.15 K and atmospheric pressure. From the experimental data, excess molar volumes VE, isentropic compressibilities κS, excess isentropic compressibilities κSE, and deviations of speeds of sound uD, have been calculated at 298.15 and 303.15 K. These excess functions have been fitted to the Redlich-Kister polynomial equation. The viscosity data have been correlated using Kendall-Monroe, Grunberg-Nissan, Tamura-Kurata, Hind-Mclaughlin Ubbelohde and Katti-Chaudhary viscosity models, and McAllister's three-body interaction model at different temperatures.  相似文献   

8.
A numerical study was performed on natural convection for water–CuO nanofluid filled enclosure where the top surface was partially exposed to convection. The cavity has a square cross-section and differentially heated. Except exposed convection part on the top, all sides are adiabatic on horizontal walls. Effects of Rayleigh number (103 ? Ra ? 105), Biot number (0 ? Bi ? ∞), length of partial convection (0.0 ? L ? 1.0) and volume fraction of nanoparticles (0.0 ? φ ? 0.1) on heat and fluid flow were investigated. The results showed that for the case of high Biot number that heat transfer along the heated was enhanced by increasing the Rayleigh number mainly at the upper portion of the heated wall. When the top wall was totally exposed to convection, the results prevail that the heat transfer was more effective at high Biot number especially at the upper portion of the heated wall. For the case of high Biot number, the results prevailed that the heat transfer at the upper portion of the heated wall increases considerably at high exposed length to convection (L); however, for L ? 0.75 the effect of L was less pronounced. Contour maps for percentage of heat transfer enhancement were presented and it was shown that the location of maximum enhancement in heat transfer was sensitive to Ra, φ and L.  相似文献   

9.
The densities ρ, speed of sound u, data of o-toluidine (i) + tetrahydropyran (j) + N,N-dimethylformamide (k) and its {tetrahydropyran (j) + N,N-dimethylformamide (k); o-toluidine (i) + N,N-dimethylformamide (k)} binaries have been measured as a function of composition at 298.15, 303.15 and 308.15 K. The excess molar enthalpies, HE data of same set of binary mixtures have also been measured over entire composition at 308.15 K. The densities and speeds of sound data of binary and ternary mixtures have been utilized to determine their excess molar volumes, VE and excess isentropic compressibilities, κSE. The observed thermodynamic properties of binary and ternary mixtures have been analyzed in terms of Graph theory. It has been observed that Graph theory correctly predicts the sign as well as magnitude of thermodynamic properties.  相似文献   

10.
11.
《Journal of Molecular Liquids》2006,123(2-3):139-145
(p, ρ, T) and (ps, ρs, Ts) properties, and apparent molar volumes Vϕ of LiI (aq) at T = 298.15 to 398.15 K, at pressures up to p = 60 MPa were reported, and apparent molar volumes at infinite dilution Vϕ0 have been evaluated. An empirical correlation for density of lithium iodide (aq) with pressure, temperature and molality was derived. The experiments were carried out at molalities m = 0.11053, 0.32532, 0.70013, 1.40459, 2.95059, and 4.88147 mol kg 1 of lithium iodide.  相似文献   

12.
To help the difficult determination of the angle γ of the unitarity triangle, Aleksan, Dunietz and Kayser have proposed the modes of the typeK ? D s + , common toB s and $\bar B_s $ . We point out that it is possible to gain in statistics by a sum over all modes with ground state mesons in the final state, i.e.K ? D s + ,K *? D s + ,K ? D s *+ ,K * D s * . The delicate point is the relative phase of these different contributions to the dilution factorD of the time dependent asymmetry. Each contribution toD is proportional to a product $F^{cb} F^{ub} f_{D_s } f_K $ whereF denotes form factors andf decay constants. Within a definite phase convention (i.e. for example the one defined by the heavy quark symmetry in the limit of heavy quarks), lattice calculations do not show any change in sign when extrapolating to light quarks the form factors and decay constants. Then, we can show that all modes contribute constructively to the dilution factor, except theP-waveK * D s *+ , which is small. Quark model arguments based on wave function overlaps also confirm this stability in sign. By summing over all these models we find a gain of a factor 6 in statistics relatively toK ? D s + . The dilution factor for the sumD tot is remarkably stable for theoretical schemes that are not in very strong conflict with data onB→ψK(K *) or extrapolated from semileptonic charm form factors, givingD tot≥0.6, always close toD(K ? D s + ).  相似文献   

13.
A high-resolution (0.003 cm−1) infrared absorption spectrum of the first overtone of the fundamental mode ν8 of methylene fluoride (CH2F2) has been measured on a Bruker IFS 120-HR Fourier transform infrared spectrometer. More than 2000 ro-vibration transitions in the range of 2770-2900 cm−1 with J ? 45 and Ka ? 20 have been assigned in this B-type band centered at 2838.5 cm−1. Precise value for the band origin (2838.579799 cm−1) and centrifugal distortion constants up to third order (ΦJK, ΦKJ, and ΦK) have been obtained by fitting a total of 1474 unblended ro-vibration transitions (J ? 45 and Ka ? 13) of the 2ν8 band with a standard deviation of 0.00029 cm−1 using a Watson’s A-reduced Hamiltonian in the Ir representation. Signature of perturbations with nearby states has been seen.  相似文献   

14.
We present first measurements on the resonance enhanced three-photon excitation in thallium, using a Nd:YAG laser pumped dye laser in conjunction with a thermionic diode ion detector. The even-parity 6s2ns2S1/2 (15 ? n ? 31) and nd 2D5/2 (13 ? n ? 42) Rydberg states have been observed. The measured level energies reveal a dynamic shift from the photoabsorption values, which is decreasing with increasing n, while the asymmetry in the line profile is observed to be increasing with increasing n. In addition, an autoionising level (sp24P3/2) adjacent to the ionization threshold has been observed and quantitatively analyzed using the Fano’s photoionization cross-section relation for an isolated autoionising resonance.  相似文献   

15.
Magnetoresistance and Hall coefficient of air-stable potassium-intercalated graphite sheets (hereafter abbreviated as K-PGS) were determined at room temperature. The magnitude of the magnetoresistance and the absolute value of Hall coefficient of K-PGS decreased with increasing potassium content of K-PGS, nK/nC. Two-carrier model was used for calculating carrier density and mobility. The electron density increased with increasing nK/nC: 3.07×1020 cm−3 (nK/nC=0.005), 5.67×1020 cm−3 (nK/nC=0.008) and 6.40×1020 cm−3 (nK/nC=0.011). The value of the electron density of K-PGS with nK/nC=0.011 (nominal composition KC91) was about 80% of the reported value, 7.8×1020 cm−3, for KC48 (nK/nC=0.021) prepared from HOPG (highly oriented pyrolytic graphite). The mobility decreased with increasing nK/nC: 2.11×103 cm2 V−1 s−1 (nK/nC=0.005), 1.42×103 cm2 V−1 s−1 (nK/nC=0.008) and 1.34×103 cm2 V−1 s−1 (nK/nC=0.011). The value of the mobility of K-PGS with nK/nC=0.011 was about 60% of the reported value (2300 cm2 V−1 s−1) for KC48 prepared from HOPG.  相似文献   

16.
Investigation of loop penguin decays of beauty hadrons seems promising in testing the predictions of the Standard Model of electroweak and strong interactions and in seeking new phenomena beyond the Standard Model. The possibility of studying the radiative penguin decays B 0K*0 γ, B 0 s, and B 0ωγ and the gluonic penguin decays B 0?K 0 S and B 0 s?? in LHCb experiments is discussed.  相似文献   

17.
The electrical transport coefficients of anti-ferromagnetic CaMnO3 have been investigated by density functional theory calculation within generalized gradient approximation. The calculated transport coefficients exhibit the anisotropic nature, in agreement with its electronic states. The transport property results reveal the stronger carrier transport along the O1–Mn–O1 plane within the O–Mn–O octahedron, indicating that the Mnd and O1p orbitals are mainly responsible for electrical transport. The maximum power factor values as a function of relaxation time reach 8.4×1023 Wm−1 K−2 s−1, 7.9×1023Wm−1 K−2 s−1 and 4.9×1023 Wm−1 K−2 s−1 within c, a and b direction, respectively. The dimensionless figure of merit ZTxx, ZTyy as well as ZTzz is estimated with 1.28, 0.8 and 1.37 at 1000 K, respectively.  相似文献   

18.
The weak phase γ is conventionally probed by theB sρ 0 mode. The predicted rate is tiny. Even if aB sρ 0 K s rate difference could be established, it would not be clear that sin 2γ had been measured, because amplitudes with other weak phases may contribute significantly. Non-CP eigenstates, such asB s D s ± K ?, have a two-fold advantage overB sρ 0 K s. Their rates are orders of magnitude above that forB sρ 0 K s, and they probe theCP-violating phase γ, without any contamination from other weak phases. Detailed time-dependent studies of non-CP eigenstates remove possible final-state phases and extract the weak phase γ.  相似文献   

19.
The double charge exchange reaction3He(K?,π +)Xn was studied at 870 MeV/c. In the X missing mass range below the sigma-nucleon production threshold (2130 MeV/c2), events were detected which can be attributed to the two-nucleon process pp(K?,π +)λn. This reaction and mass range also offers good prospects for finding theI=1/2,l=1 (1 P1) spin-singlet dibaryon Ds suggested as the lowest massS=?1 dibaryon in the MIT Bag Model. Although the existence of the Ds is not ruled out by the present data, there is no need to invoke such an object to account for the observed events below σ production threshold. We show that the cross section level for these events is compatible with a dominant two-nucleon mechanism K?p→π 0λ,π 0p →π +n. We also offer an interpretation of the recent (K?,K+) data on nuclear targets from Iijimaet al., which display a broad peak centered around a K+ momentum of 600 MeV/c. We find that the two-nucleon mechanism K?N →πY,πN→K+Y produces cross sections which are at least an order of magnitude smaller than those observed, and we suggest that the one nucleon process K?p →Φλ, followed by the decayΦ → K+K?, accounts for the data.  相似文献   

20.
Results are presented on two-particle inclusive production inK + p interactions at 32 GeV/c. We study thex 1,2=x 1+x 2 dependence of invariant structure functions of (ππ)-pairs and compare them to single particle inclusive distributions in the fragmentation regions. Distributions of particles observed at Feynmanx 2 in association with various “trigger” particles or systems atx 1 in the same hemisphere are dicussed in terms of the reduced variable \(\tilde x_2 = x_2 /(1 - |x_1 |)\) . We further present absolute production rates and production ratios of π+'s and π?'s associated with π±,K s 0 , Λ, \(\bar \Lambda \) ,K *+ (890), (K s 0 π+), and (π+ π?)-triggers, and compare them with qualitative predictions of the quark recombination model. Forwardbackward correlations between (K s 0 π±), (K s 0 ,p), (Λ, π?), \((\bar \Lambda \pi ^ \pm )\) , and (p, π?) pairs are also discussed.  相似文献   

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