Biomedical subjects

Yu-Feng Hu

Publications and source records attributed to Yu-Feng Hu.

5 recordsLinked to original sources

PubMed2006

The semi-ideal solution theory for mixed ionic solutions at solid-liquid-vapor equilibrium.

The semi-ideal solution theory has been presented to describe the changes in thermodynamic properties accompanying the process of mixing the nonideal electrolyte solutions M(i)X(i)-(NY)sat-H2O (i = 1 and 2) at constant activities of NY and H2O, including concentration, chemical potential, activities of all M(i)X(i), Gibbs free energy, enthalpy, entropy, thermal properties, and volumetric properties. The theory states that, under the conditions of equal activities of NY and H2O, the average hydration numbers characterizing the ion-solvent interactions have the same values in the mixture as in the subsystems and the process of mixing these nonideal electrolyte solutions is as simple as that of mixing the ideal solutions if the contributions from the ion-ion interactions to the solvent activity are assumed to be the same in the mixture as in its subsystems, which has been justified by the calculations of the Pitzer equation. Therefore, a series of novel linear equations are established for the thermodynamic properties accompanying the process of mixing these nonideal solutions as well as mixing the ideal solutions M(i)X(i)-(NY)sat-H2O (i = 1 and 2) of equal mole fractions of NY and H2O. From these equations, the widely applied empirical Zdanovskii's rule is derived theoretically, and the important constant in the McKay-Perring equation under isopiestic equilibrium is determined theoretically, which has been substantiated by comparisons with the experimental results for 18 mixtures reported in the literature. Isopiestic measurements have been made for the systems BaCl2-LaCl3-H2O, NaCl-BaCl2-LaCl3-H2O, and NaCl-LaCl3-BaCl2.2H2O(sat)-H2O at 298.15 K. The results are used to test the novel linear concentration relations, and the agreement is excellent. The novel predictive equation for the activity coefficient of M(i)X(i) in M1X1-M2X2-(NY)sat-H2O has been compared with the calculations of the Pitzer equation, and the agreement is good.

Journal Article↗

PubMed2006

Linear and star-shaped polynuclear Ru(II) complexes of 2-(2'-pyridyl)benzimidazolyl derivatives: syntheses, photophysical properties and red light-emitting devices.

Two new star-shaped ligands with a 1,3,5-triphenylbenzene core, tmpb (1,3,5-tris[p-2-(2'-pyridyl)benzimidazolylphenyl]benzene), and a 2,4,6-tris(p-biphenyl)-1,3,5-triazine core, tmbt (2,4,6-tris[p-2-(2'-pyridyl)benzimidazolylbiphenyl]-1,3,5-triazine), have been synthesized. Their corresponding trinuclear Ru(II) complexes [Ru3(tmpb)(bpy)6](PF6)6 (3) and [Ru3(tmpt)(bpy)6](PF6)6 (4) have been obtained. Two dinuclear linear Ru(II) complexes with previously reported ligands bmb (1,4-bis[2-(2'-pyridyl)benzimidazolyl]benzene) and bmbp (4,4'-bis[2-(2'-pyridyl)benzimidazolyl]biphenyl) and formulae [Ru2(bmb)(bpy)4](PF6)4 (1) and [Ru2(bmbp)(bpy)4](PF6)4 (2) have also been synthesized. Photophysical and electrochemical properties of the new compounds have been investigated. All four compounds display a characteristic metal-to-ligand-charge transfer (MLCT) absorption band and emit a red light when excited at the maximum of the MLCT band with emission maximum at 624, 629, 623 and 625 nm, respectively in neat films at ambient temperature. The emission quantum efficiency of the four complexes in neat films was determined to be 0.15, 0.17, 0.04 and 0.05, respectively. Light emitting devices based on these four compounds were fabricated by spin-casting the compound as a neat film to an ITO substrate, followed by the deposition of an aluminium metal layer. All devices emit a deep red light and the device behavior resembles that of a light emitting electrochemical cell. The EL maximum of the devices 1, 2, 3, and 4 is at 637, 657, 678, and 655 nm, respectively. All four devices have a fast response time when a sufficiently high voltage is applied. The device based on 2 is the brightest with a maximum luminance of 133 cd m(-2) at 7 V. The performance of devices based on 1, 2, and 4 is in general much more efficient than the device based on [Ru(bpy)3](PF6)2, which was fabricated and evaluated under the same experimental conditions as for the devices based on 1-4.

Journal Article↗

PubMed2005

Effect of the structures of ionic liquids and alkylbenzene-derived amphiphiles on the inhibition of asphaltene precipitation from CO2-injected reservoir oils.

The inhibition of asphaltene precipitation from high-pressure, CO(2)-injected reservoir oils by ionic and nonionic amphiphiles, the ionic liquids based on p-alkylpyridinium ([C(n)()py](+)) and N-butylisoquinolinium ([C(4)iql](+)) cations, and the alkylbenzene-derived amphiphiles p-alkylphenol (C(n)()phol), p-alkylbenzenesulfonic acid (C(n)()bsa), and sodium p-alkylbenzenesulfonate (C(n)()bsNa) was investigated for the first time. The influences of the structures of these compounds and the effect of the combination of their cations and anions were studied. The results show that the inhibition abilities of the alkylbenzene-derived amphiphiles first increase when n = 2-8 and then remain almost constant when n >/=8 and that the effectiveness follows the order C(n)()phol < C(n)()bsa approximately C(n)()bsNa. The inverse trend is observed for the ionic liquids [C(n)()py][Cl]; that is, their inhibition abilities decrease as n increases from 4 to 8 to 12. [C(4)iql][Cl] is more effective than [C(4)py][Cl], but [C(n)()py][BF(4)] and [C(n)()py][PF(6)] have almost no effect on the stabilization of asphaltenes. It was found that the effectiveness of an alkylbenzene-derived amphiphile on the inhibition of asphaltene precipitation from reservoir oils relies on its ability to form a stable steric-stabilization layer around asphaltenes, which is controlled by the polarity of its headgroup and the length of its alkyl tail. The novel mechanism of inhibiting asphaltene precipitation using the ionic liquids [C(n)()py] ([Cl], [BF(4)], and [PF(6)]) and [C(4)iql][Cl] was proposed. The mechanism states that the ionic liquids can effectively prevent asphaltene precipitation from the reservoir oils by breaking the asphaltene associations, which are due to the local nonneutrality of the charge densities of the cation and the anion. The ionic liquids that are based on an anion with high charge density, in connection with cations with sufficiently low charge densities, can effectively inhibit asphaltene precipitation from the reservoir oils. This mechanism is also important for studying the thermodynamic properties and phase behavior of the ionic liquids.

Journal Article↗

PubMed2005

[Quality of life in the treatment assessment of postmenopausal osteoporosis].

OBJECTIVE: To evaluate quality of life (QOL) in the treatment assessment of postmenopausal osteoporosis (PMOP) by comparing the QOL of three treatments: hormone replacement treatment, supplement of calcium and vitamin D and risedronate. METHODS: All patients with postmenopausal osteoporosis (PMOP) in this clinical trial had been allocated into 4 groups: placebo therapy group, vitamin D addition calcium therapy group, hormone replacement treatment (HRT) therapy group, and risedronate therapy group. We measured the bone mineral density (BMD) and quality of life sale (QOLS) of patients in three times, before the treatment, 3 months after the treatment,and 12 months after the treatment. The differences of the QOL and BMD at the 4 groups and at different time, the linear correlation of the change of QOL and the change of BMD, were both compared after the measurement. RESULTS: The total score of QOL and the score of disease domain and physical domain of HRT therapy group and risedronate therapy group were higher than the placebo therapy group (F = 17. 335, P <0.001), but vitamin D addition calcium therapy group was not different from that of the placebo therapy group. The score of other three domains had no statistically significant difference among the 4 groups. The score of disease domain of the patients of risedronate therapy group started to increase after 3 months of treatment, and continued to increase after 12 months of treatment. The score of disease domain of the patients of HRT therapy group started to increase only after 12 months of treatment. But the score of disease domain of the patients of vitamin D addition calcium therapy group did not increase after 12 months of treatment. The changes of the score of disease domain had the linar correlation with the changes of BMD, and the correlation coefficient was from 0.608 to 0.827. CONCLUSION: QOL may become one of the indexes of medical treatment outcome assessment system for PMOP.

Absorptiometry, Photon↗

PubMed2004

Prediction of the surface tension of mixed electrolyte solutions based on the equation of Patwardhan and Kumar and the fundamental Butler equations.

The predictive equation of Patwardhan and Kumar for the water activity of mixed electrolyte solutions has been used together with the fundamental Butler equations to establish a new simple predictive equation for the surface tension of mixed electrolyte solutions. This newly proposed equation can provide the surface tensions of multicomponent solutions using only the data of the corresponding binary subsystems of equal ionic strength. No binary interaction parameters are required. The predictive capability of the equation has been tested with the experimental data for 26 concentrated multicomponent electrolyte solutions at different temperatures and compared with the model of Li et al. Both equations agree well with the experimental results of systems examined over entire experimental composition ranges, but the new equation generally gives better predictions for most 1:1 electrolyte systems examined, and considerable improvement in predictions has been achieved for all the mixtures containing 1:2 and 2:2 electrolytes and for 1:1 electrolyte systems at higher temperatures.

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