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1.
Lamellar Liquid Crystals of Brij 97 Aqueous Solutions Containing Different Additives 总被引:1,自引:0,他引:1
Lamellar liquid crystals of Brij 97 aqueous solutions were investigated by means of rheological techniques and SAXS at 25 °C,
in the presence of various additives including isopropyl myristate, oleic acid, ionic liquid bmim-PF6 and bmim-BF4. The lamellar phases show high elasticity as indicated by their mechanical and discrete relaxation spectra, which is expected
to be an advantage when they are used as drug delivery vehicles. It is noted that in comparison with other systems, the lamellar
phase formed in the Brij 97/water/IPM system has the lowest storage and loss moduli, implying that it has a weak network strength
and less stable internal structure. The Brij 97/water/oleic acid system is the most shear resistance, whereas the Brij 97/water/bmim-PF6 system exhibits fluid-like viscoelastic properties to some extent. These differences are analyzed through SAXS data for the
different location of the additive in the lamellar phase. 相似文献
2.
Yihua Li Wenge Yang Tuan Zhang Chaoyuan Wang Kai Wang Yonghong Hu 《Journal of solution chemistry》2013,42(12):2342-2353
Solubility data were measured for omeprazole sulfide in ethanol, 95 mass-% ethanol, ethyl acetate, isopropanol, methanol, acetone, n-butanol and n-propanol in the temperature range from 280.35 to 319.65 K by employing the gravimetric method. The solubilities increase with temperature and they are in good agreement with the calculated solubility of the modified Apelblat equation and the λh equation. The experimental solubility and correlation equation in this work can be used as essential data and model in the purification process of omeprazole sulfide. The thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy were calculated using the van’t Hoff equation. 相似文献
3.
Yonit Sembira-Nahum Alexander Apelblat Emanuel Manzurola 《Journal of solution chemistry》2008,37(3):391-401
Densities of aqueous solutions of L-glutamic acid and magnesium-L-glutamate were determined from T=288.15 to 333.15 K at 5 K temperature intervals. The measured densities were used to evaluate the apparent molar volumes,
V
2,φ
(m,T), the cubic expansion coefficients, α(m,T), and the changes of isobaric heat capacities with respect to pressure, (∂
C
p
/∂
p)
T,m
. They were qualitatively correlated with changes in the structure of water that occur when L-glutamic acid or magnesium-L-glutamate
are present. 相似文献
4.
Song Guo Wenge Yang Yonghong Hu Kai Wang Yuanyuan Luan 《Journal of solution chemistry》2013,42(10):1879-1887
The solubility of N-acetylglycine was measured in methanol, ethanol, propanol, isopropanol, n-butanol and ethyl formate in the temperature range between 278.15 and 319.15 K under atmospheric pressure by a gravimetric method. The solubility of N-acetylglycine in those selected solvents increases with increasing temperature. The solubility data were correlated with the van’t Hoff equation, the modified Apelblat equation and the λh equation to obtain the corresponding model parameters. The experimental results could be useful for optimizing the industrial process of purification of N-acetylglycine. 相似文献
5.
B. Hemalatha P. Vasantharani K. Karthikeyani Vijayakumari 《Journal of solution chemistry》2009,38(8):947-955
Density (ρ), viscosity (η) and ultrasonic velocity (U) of tetraethylammonium bromide (TEAB) and tetrapropylammonium bromide (TPAB) in 10, 20 and 30% of N,N-dimethylformamide (DMF)
and water mixtures have been measured as a function of electrolyte concentration at 303, 308 and 313 K. The experimental values
of ρ,η and U are used to calculate free volume (V
f), internal pressure (π
i), solvation number (S
n) and viscosity B-coefficient. These parameters are used to discuss the ion-solvent and ion-ion interactions and structure making tendency
of the electrolyte. 相似文献
6.
Simultaneous measurements with magnesium ion-selective and pH glass electrodes have been used for determination of the stability
constants of magnesium ions with various biologically relevant ligands by alkalimetric titration under physiological conditions
(37 ○C, I=0.15 mol⋅dm−3). New systems were investigated: magnesium with pyroglutamate, pyridoxine and HEPES, along with citrate, lactate, glycinate,
aspartate and glutamate. For comparison, calcium stability constants with the same ligands were determined similarly, using
calcium ion-selective and pH glass electrodes. Ligand protonation constants, necessary for the calculation of the metal complex
formation constants, were also determined. 相似文献
7.
Raphael da C. Cruz Rosana J. Martins Márcio J. E. de M. Cardoso Oswaldo E. Barcia 《Journal of solution chemistry》2009,38(8):957-981
Density measurements were made for binary aqueous solutions of polyethylene glycol at seven temperatures: 283.15, 288.15,
293.15, 298.15, 303.15, 308.15, and 313.15 K. Polyethylene glycol samples with nominal average molar masses of 3000 g⋅mol−1 (PEG 3000), 6000 g⋅mol−1 (PEG 6000), 10000 g⋅mol−1 (PEG 10000) and 20000 g⋅mol−1 (PEG 20000) were used. These results were used to determine the specific volumes of solutions with solute-to-solvent mass
ratios (mass of the solute/mass of the solvent) in the range 0.0546 to 1.4932 for PEG 3000, from 0.0553 to 1.4986 for PEG
6000, from 0.0552 to 1.2241 for PEG 10000, and from 0.0530 to 1.2264 for PEG 20000. The differences between the specific volume
of a solution and the specific volume of the pure solvent, at a given temperature, were represented by a virial-type equation
in terms of solute concentration. The first-order coefficient of the expansion is the partial specific volume of the solute
at infinite dilution. The higher-order coefficients are related to the contribution of pairs, triplets, and higher-order solute
aggregates, according to the Constant-Pressure Solution Theory. The functional dependence of the virial coefficients upon
temperature is discussed in terms of solute-solute and solute-solvent interactions. The effect of the PEG molar mass on the
partial specific volume of solute at infinite dilution, as well as the contributions of pairs of solute molecules to the solution
volume, are also investigated. The apparent specific volume, apparent specific expansibility, apparent specific expansibility
at infinite dilution and virial coefficients of the apparent specific expansibility are also presented. 相似文献
8.
9.
Density, speed of sound and refractive index of the imidazolium-based ionic liquids (ILs), 1-methyl-3-octylimidazolium chloride
[C8mim][Cl], 1-butyl-3-methylimidazolium methyl sulfate [C4mim][C1OSO3], and 1-butyl-3-methylimidazolium octyl sulfate [C4mim][C8OSO3], have been measured in the temperature range from 283.15 to 343.15 K. Experimental density and speed of sound have been
used to calculate the internal pressure p
i of the ILs. The p
i values were found to be higher than those of water and molecular organic liquids, but lower than those of classical molten
salts. We also calculated molar refraction R
M from the measured refractive index n
D in the temperature range from 288.15 to 343.15 K. Refractive indices of ILs were also higher than those of normal organic
liquids, but comparable to long-chain hydrocarbon organic solvents. The structure-property correlation of the ILs has been
discussed and the results have been compared to our earlier studies (Kumar in J. Solution Chem. 37:203–214, 2008). 相似文献
10.
The disaccharide isomaltose is produced via an enzymatic reaction and is adsorbed to BEA zeolite. This reaction integrated
adsorption can be achieved as fluidized bed as well as fixed bed. We investigated isotherms, adsorption enthalpies and sorption
kinetics of BEA zeolite and extrudates with a novel aluminum phosphate sintermatrix. These extrudates contain 50% (w/w) of
BEA 150 zeolites (Si/Al = 75) as primary crystals. BET-surface for extrudates is 245 m2⋅g−1 and 487 m2⋅g−1 for zeolite. Extrudates show a monomodal macropore structure with a maximum at 90 nm. All isotherms show a type I shape.
For lower equilibrium concentrations, which occur during the enzymatic reaction, Henry’s law is applied and compared to a
Langmuir model. Adsorption equilibrium constant K
i,L
calculated from Langmuir for extrudates at 4 °C is 64.7 mL⋅g−1 and more than twice as high as obtained from Henry’s law with K
i
is 26.8 mL⋅g−1. Adsorption on extrudates at 4 °C is much stronger than on zeolite crystals where the Henry coefficient K
i
is 17.1 mL⋅g−1. Adsorption enthalpy Δh
Ad calculated from van’t Hoff plot with the Henry equation is −44.3 kJ⋅mol−1 for extrudates and −29.6 kJ⋅mol−1 for zeolite crystals. Finally, the kinetics for ad- and desorption were calculated from the initial slope. The diffusion
rate for ad- and desorption on extrudates were in the same range while adsorption on zeolites is three orders of magnitudes
faster than desorption. 相似文献
11.
A homopolymer of methyl methacrylate (MMA) and its copolymer with styrene at different compositions were synthesized and characterized.
Viscosity measurements of the synthesized homopolymer and the copolymers in toluene solutions were performed at 313 K. Different
equations were used to calculate the intrinsic viscosity, viscometric constants values, and molecular weight of the synthesized
polymers. The values of intrinsic viscosity and viscosity average molecular weight obtained by the two methods (single point
determination and graphical extrapolation) were compared in order to verify the validity of the single point determination
for the polymers. Viscometric properties derived included the specific viscosity (it determines the contribution of the solute
to the viscosity of the solution), the reduced viscosity (that provides a measure of the polymer capacity for increasing the
solution viscosity), and the intrinsic viscosity. 相似文献
12.
Poly-ortho-methylanilines (POT) in three states fully oxidized, fully reduced and oxidized in varying degrees were synthesized by the reaction of common POT (C-POT) having nearly equal amounts of benzenediamine and quinonediimine units with iodine or phenylhydrazine, and the resulting polymers were characterized by IR,~(13)C-NMR, SEM and elemental analysis. The results showed that the quinonediimine unit in C-POT could be reduced by phenylhydrazine to the benzenediamine unit,forming the polymer with low OD (oxidation degree) or in a fully reduced state and that iodine-oxidation resulted in the increase of quinonediimine unit and decrease of benzenediamine unit. The solubility and flexibility of the formed polymers depend strongly on the amount of quinonediimine unit in it. It is necessary to reduce the content of quinonediimine structure unit in order to improve the solubility of aniline-class polymers. 相似文献
13.
Mandana Behbahani Mokhtar Nosrati Hassan Mohabatkar 《Applied biochemistry and biotechnology》2018,185(3):786-798
Lysozyme is a relatively small enzyme with different biological activities, which is found in tears, saliva, egg white, and human milk. In the study, the anti-HIV-1 activity of lysozymes purified from quail, Meleagris, and hen egg white has been determined. For this end, a time-of-drug-addition assay was performed to identify the target of anti-HIV-1 agents and for determination of probable anti HIV-1 mechanism of the studied lysozyme, the binding affinity of the lysozymes to the human CD4 receptor was studied by molecular docking method. To define structural differences between studied lysozymes, structural motifs of them were predicted by MEME tool. Quail, hen, and Meleagris lysozymes showed potent anti-HIV-1 activity with EC50 of 7.5, 10, and 55 nM, respectively. The time-of-drug-addition study demonstrated that the inhibitory effect of all purified lysozymes is before HIV-1 infection. The frequency and intensity of CD4 expression in PBMCs decreased in the presence of all mentioned lysozymes. Also, the expression level of C-C chemokine receptor type 5 (CCR5) and chemokine receptor type 4 (CXCR4) on CD4+ T cells was not changed in cells treated with these lysozymes. The results of in silico study confirmed that the binding energy of quail lysozyme with CD4 was more than that of other studied lysozymes. The results revealed that these lysozymes restrict HIV-1 attachment to host cell CD4. 相似文献
14.
The paper discusses the ground state properties and dynamics of monolayer films formed by atomic adsorbates on a square lattice,
being the (100) plane of a face centered cubic crystal. The vibrations of films ordered into the commensurate c(2×2) as well as into the recently discovered ordered phase exhibiting a distorted Archimedean tiling of the type (32.4.3.4) are considered. The dispersion relations and the densities of states are determined and discussed. 相似文献
15.
Apparent molar volumes V
φ,B of n-propylamine, n-butylamine, di-n-propylamine, di-n-butylamine, triethylamine, tri-n-propylamine, and tri-n-butylamine in 1,4-dioxane and in oxolane (tetrahydrofuran) have been determined at 303.15 K using a high-precision Anton
Paar vibrating-tube densimeter (model DMA 60/602). The limiting partial molar volumes
and limiting excess partial molar volumes
are analyzed and interpreted in terms of solute-solvent interactions and structural effects of the molecules.
Analyses were made of the contributions of specific interactions to the partial molar volumes of these primary, secondary
and tertiary amines in 1,4-dioxane and oxolane using the Terasawa model, scaled particle theory (SPT) and hard-sphere theory
(HST). The ERAS model has also been applied to estimate the apparent molar volumes and excess apparent molar volumes of alkylamine
solutions in 1,4-dioxane and oxolane. 相似文献
16.
Heats of solution, Δsol
H
m
, of L-cysteine, L-serine and L-asparagine amino acids have been measured at different concentrations of aqueous ethanol,
propanol and 2-propanol at 298.15 K using solvation calorimetry. These data are compared with the results reported earlier
for L-alanine in ethanol. The enthalpic coefficients, h
xy
, of the solute-organic cosolvent pair interaction in water have been obtained from the McMillan-Mayer approach and the data
have been interpreted in terms of various interactions and changes in solvent structure. 相似文献
17.
Study on biotinylation strategies for competitive immunoassay of estradiol (E2) was carried out. Two types of competitive enzyme immunoassay (EIA) with Biotin-Avidin amplification system were established and optimized.The E2-Biotin conjugate was used as a tracer in one assay, and biotinylated antibody was used as a tracer in the other. In both of EIAs, horseradish peroxidase-labelled Avidin (Avidin-HRP) was used with a spectrometric determination of enzyme activity. The precision, sensitivity and specificity were measured and compared. The results showed that although both were satisfactory in specificity, the EIA with hapten-Biotin showed to be superior to the EIA with biotinylated antibody in sensitivity and precision. The limit of detection of serum E2 was 8 and 50 pg/mL with E2-Biotin and biotinylated antibody as tracer, respectively. 相似文献
18.
Zhongyong Zha Dingna Wang Wei Hong Li Liu Sai Zhou Xiaojie Feng Bing Qin Jianmei Wang Yi Yang Liang Du Dong Zhang Zhendong Fang Chuanqin Xia 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(1):257-262
This study aimed at influence of europium speciation on its accumulation in Brassica napus (CK) and over-expressing BnTR1 lines (OE), and the kinetics of Eu uptake were investigated. These results indicated that the uptake in the roots of OE was higher than that of CK at high concentrations of europium and even the enrichment in the roots of OE was as high as 20,000 mg/kg at 328.9 μΜ Eu, this suggested that OE might have better resistance to uranium than CK. The time kinetics in plants showed that there had the similar trend between CK and OE. The formation of Eu3+at pH 5 in deionized water was beneficial to plants enrichment Eu and carbonate could reduce the adsorption of Eu in two group and phosphate almost completely impress the adsorption of Eu in two group, but citric acid could enhance europium root-to-shoot translocation in two group. These results would help understanding the mechanism of Eu uptake in Brassica napus (CK) and over-expressing BnTR1 lines (OE), therefore properly developing efficient europium/americium phytoremediation. 相似文献
19.
MinGU FangZuYANG LingHUANG ShiBingYAO ShaoMinZHOU 《中国化学快报》2004,15(8):981-984
The nucleation mechanisms of cobalt from sulfate solutions were studied by utilizing the electrochemical technique, chronoamperometry. It was found that the recorded current-time transients introduced from 1.0mol/L CoSO4 solution were complexes with unusual shapes. All characteristic features were identified as separate process. The instantaneous or progressive nucleation with 2D or 3D growth exists during the cobalt deposition, depending on the applied potentials. 相似文献
20.
Pasquale Crea Concetta De Stefano Mutsa Kambarami Frank J. Millero Virender K. Sharma 《Journal of solution chemistry》2008,37(9):1245-1259
The protonation constants for oxidized glutathione, H
i−1L(4−i+1)−, K
i
H=[H
i
L(4−i)−]/[H
i−1L(4−i+1)−][H+] i=1,2,…,6 have been measured at 5, 25 and 45 °C as a function of the ionic strength (0.1 to 5.4 mol⋅[kg(H2O)]−1) in NaCl solutions. The effect of ionic strength on the measured protonation constants has been used to determine the thermodynamic
values (K
i
H0) and the enthalpy (ΔH
i
) for the dissociation reaction using the SIT model and Pitzer equations. The SIT (ε) and Pitzer parameters (β
(0), β
(1) and C) for the dissociation products (L4−, HL3−, H2L2−, H3L−, H4L, H5L+, H6L2+) have been determined as a function of temperature. These results can be used to examine the effect of ionic strength and
temperature on glutathione in aqueous solutions with NaCl as the major component (body fluids, seawater and brines). 相似文献