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61.
V. A. Davankov L. A. Onuchak S. Yu. Kudryashov Yu. I. Arutyunov 《Chromatographia》1999,49(7-8):449-453
Summary A systematic derivation of corresponding equations shows that averaging the pressure and the flow rate of the mobile phase
in a gas chromatographic column over the column length and over the time that an unretained component resides in the column,
requires the use of three different compressibility correction factors,j
2
1
,j
3
2
, andj
4
3
. When multiplied by the adjusted retention volume,V
R-VM, the Martin and James mobile phase compressibility correction factorj
3
2
, only, produces the value of specific retention volume,V
g
T
, which is connected unambiguously with the thermodynamic phase distribution coefficient,K, of the sorbate. 相似文献
62.
KMnF3 and DKDP crystals have been studied around their phase transitions using a conduction calorimetry technique where a long periodical square thermal pulse (0.05 K in amplitude) is superposed to a heating or cooling ramp as low as 0.06 K h−1. Specific heat data obtained in the dissipation and relaxation semiperiods of the square pulse become different inside the phase transition interval. The electromotive force developed by the heat fluxmeters at the end of the relaxation semiperiod (underlying signal) is compared with the DTA trace obtained in a second run with the same temperature ramp but without the modulated perturbation. The comparison between the DTA trace and specific heat data obtained in the first run allows us to determine the value of the latent heat and to obtain information about the kinetic of the phase transition. 相似文献
63.
64.
W. Wasiak 《Chromatographia》1987,23(4):261-264
Summary Interactions of Cu(II) complexes chemically bonded to the surface of silica with chloro-derivatives of alkanes and alkenes
were investigated. It was found that chlorine as a substituent exerts a considerable influence on the retention of the individual
chloro-derivatives. In the case of chloroalkenes this influence is negative while in the case of chloroalkanes it is positive.
The magnitude of the observed effect depends on the number of substituents and on the way of their distribution within the
molecule.
Part III of a series on transition metal complexes in GC. Part II see ref. [1]. 相似文献
65.
66.
Mixing ionic liquids (ILs) has been revealed as a useful way to finely tune the properties of IL-based solvents. The scarce available studies on IL mixtures have shown a quasi-ideal behavior of their physical properties. In this work, we have performed a thermophysical characterization of two binary IL mixtures, namely {4-methyl-N-butylpyridinium bis(trifluoromethylsulfonyl)imide ([4bmpy][Tf2N]) + 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4])} and {[4bmpy][Tf2N] + 1-ethyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate [emim][TFES]}. Both binary IL mixtures have been recently proposed as promising solvents in the (liquid + liquid) extraction of aromatic hydrocarbons from mixtures with alkanes. Densities, viscosities, refractive indices, thermal stability, and specific heats of the {[4bmpy][Tf2N] + [emim][EtSO4]} and {[4bmpy][Tf2N] + [emim][TFES]} IL mixtures have been measured as a function of both temperature and composition. Dynamic viscosities, refractive indices, and thermal stability of the {[4bmpy][Tf2N] + [emim][EtSO4]} mixture have exhibited strong deviations from the ideality, in contrast with the quasi-ideal properties of the {[4bmpy][Tf2N] + [emim][TFES]} mixture and the behavior of the imidazolium and pyridinium-based IL mixtures studied hitherto. The reliability of predictive methods of the thermophysical properties of the mixtures has also been evaluated. 相似文献
67.
Alexei A. Belik Pan?e Naumov Jungeun Kim Shunsuke Tsuda 《Journal of solid state chemistry》2011,184(11):3128-3133
Low-temperature structural properties of the synthetic mineral libethenite Cu2PO4OH were investigated by single-crystal X-ray diffraction, synchrotron X-ray powder diffraction, specific heat measurements, and Raman spectroscopy. A second-order structural phase transition from the Pnnm symmetry (a=8.0553(8) Å, b=8.3750(9) Å, c=5.8818(6) Å at 180 K) to the P21/n symmetry (a=8.0545(8) Å, b=8.3622(9) Å, c=5.8755(6) Å, β=90.0012(15) at 120 K) was found at 160 K during cooling. At 120 K, the monoclinic angle is 90.0012(15) from single crystal X-ray data vs 90.083(1) from powder X-ray diffraction data. The P21/n–to–Pnnm transition may be a general feature of the adamite-type compounds, M2XO4OH. 相似文献
68.
Yoshitaka Misawa 《Journal of solid state chemistry》2011,184(6):1478-1483
Structures and magnetic properties of double perovskite-type oxides Eu2LnTaO6 (Ln=Eu, Dy-Lu) were investigated. These compounds adopt a distorted double perovskite structure with space group P21/n. Magnetic susceptibility, specific heat, and 151Eu Mössbauer spectrum measurements show that the Eu2+ ions at the 12-coordinate sites of the perovskite structure are antiferromagnetically ordered at ∼4 K, and that Ln3+ ions at the 6-coordinate site are in the paramagnetic state down to 1.8 K. 相似文献
69.
Coral reef-like PANI nanotubes composed of nanopaticles were successfully synthesized by a reactive template of manganese oxide.The structure was characterized by using SEM,TEM,and FT-IR,and the supercapacitive behaviors of these nanotubes were investigated with cyclic voltammetry(CV),and charge-discharge tests,respectively.A maximum specific capacitance of 533 F/g could be achieved in 1mol/L aqueous H2SO4 with the potential range of -0.2 to 0.8 V(vs.the saturated calomel electrode) in a half-cell setup configuration for PANI electrode,suggesting its potential application in the electrode material for electrochemical capacitors. 相似文献
70.
Junfeng Wang Yanping Huang Yanlin Wang 《International Journal of Heat and Fluid Flow》2011,32(5):982-992
A simultaneous visualization and measurement study on some specific points on demand curves, such as onset of nucleate boiling (ONB), onset of significant void (OSV), onset of flow instability (OFI), and two-phase flow patterns in a single-side heated narrow rectangular channel, having a width of 40 mm and a gap of 3 mm, was carried out. New experimental approaches were adopted to identify OSV and OFI in a narrow rectangular channel. Under experimental conditions, the ONB could be predicted well by the Sato and Matsumura model. The OSV model of Bowring can reasonably predict the OSV if the single-side heated condition is considered. The OFI was close to the saturated boiling point and could be described accurately by Kennedy’s correlation. The two-phase flow patterns observed in this experiment could be classified into bubbly, churn, and annular flow. Slug flow was never observed. The OFI always occurred when the bubbles at the channel exit began to coalesce, which corresponded to the beginning of the bubbly–churn transition in flow patterns. Finally, the evolution of specific points and flow pattern transitions were examined in a single-side heated narrow rectangular channel. 相似文献