Rationale
The SrO–Al2O3 system holds promise as a base for a wide spectrum of advanced materials, which may be synthesized or applied at high temperatures. Therefore, studying vaporization and ...high‐temperature thermodynamic properties of this system is of great practical importance.
Methods
Samples of the SrO–Al2O3 system were obtained by solid‐state synthesis and identified by X‐ray fluorescence analysis, X‐ray phase analysis, scanning electron microscopy, electron probe microanalysis, simultaneous thermal analysis, and thermogravimetric analysis. The thermodynamic properties of the SrO–Al2O3 system were studied by the Knudsen effusion mass spectrometric (KEMS) method and were fitted by the Redlich–Kister and Wilson polynomials. The thermodynamic values obtained were also optimized within the generalized lattice theory of associated solutions (GLTAS).
Results
The vapor composition, temperature, and concentration dependences of the partial vapor pressures over the samples under study as well as the SrO activities in melts of the SrO–Al2O3 system were determined by the KEMS method. Usage of the Redlich–Kister and Wilson polynomials allowed calculation of the excess Gibbs energies, enthalpies of mixing, and excess entropies in the concentration range 0–33 mol% of SrO at temperatures of 2450 and 2550 K.
Conclusions
Significant negative deviations from the ideality were observed in the melts of the SrO–Al2O3 system at 2450, 2550, and 2650 K. The Wilson polynomial was found to be the optimal approach to describe the thermodynamic properties in the system studied. Optimization of the experimental data using the GLTAS approach allowed the characteristic features of the thermodynamic description of the SrO–Al2O3 system to be elucidated and explained.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The SrO-Al
O
system holds promise as a base for a wide spectrum of advanced materials, which may be synthesized or applied at high temperatures. Therefore, studying vaporization and high-temperature ...thermodynamic properties of this system is of great practical importance.
Samples of the SrO-Al
O
system were obtained by solid-state synthesis and identified by X-ray fluorescence analysis, X-ray phase analysis, scanning electron microscopy, electron probe microanalysis, simultaneous thermal analysis, and thermogravimetric analysis. The thermodynamic properties of the SrO-Al
O
system were studied by the Knudsen effusion mass spectrometric (KEMS) method and were fitted by the Redlich-Kister and Wilson polynomials. The thermodynamic values obtained were also optimized within the generalized lattice theory of associated solutions (GLTAS).
The vapor composition, temperature, and concentration dependences of the partial vapor pressures over the samples under study as well as the SrO activities in melts of the SrO-Al
O
system were determined by the KEMS method. Usage of the Redlich-Kister and Wilson polynomials allowed calculation of the excess Gibbs energies, enthalpies of mixing, and excess entropies in the concentration range 0-33 mol% of SrO at temperatures of 2450 and 2550 K.
Significant negative deviations from the ideality were observed in the melts of the SrO-Al
O
system at 2450, 2550, and 2650 K. The Wilson polynomial was found to be the optimal approach to describe the thermodynamic properties in the system studied. Optimization of the experimental data using the GLTAS approach allowed the characteristic features of the thermodynamic description of the SrO-Al
O
system to be elucidated and explained.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The ultrafast photochemistry of the Cr(NCS)63– complex upon excitation to the 4T2 ligand-field (LF) state was studied in dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) in a wide temporal ...range (100 fs to 9 ms) by a combination of femtosecond and nanosecond transient absorption spectroscopy techniques and supported by quantum-chemical DFT/TD-DFT calculations. The initially excited 4T2 state undergoes intersystem crossing to the vibrationally hot 2E state with time constants of 1.1 ± 0.2 and 1.8 ± 0.1 ps in DMSO and DMF, respectively. Vibrational relaxation occurs in the same time scale and takes 1–5 ps. A major part of the Cr(NCS)63– complex in the 2E state undergoes intersystem crossing to the ground state with time constants of 65 ± 5 and 85 ± 5 ns in DMSO and DMF, respectively. A minor part of electronically excited Cr(NCS)63– undergoes irreversible photochemical decomposition. In DMSO, the photolysis of the Cr(NCS)63– complex results in single or double isothiocyanate ion release followed by the coordination of the solvent molecules with a time constant of 1 ± 0.2 ms.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Metabolic fingerprinting is a powerful analytical technique, giving access to high-throughput identification and relative quantification of multiple metabolites. Because of short analysis times, ...matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is the preferred instrumental platform for fingerprinting, although its power in analysis of free fatty acids (FFAs) is limited. However, these metabolites are the biomarkers of human pathologies and indicators of food quality. Hence, a high-throughput method for their fingerprinting is required. Therefore, here we propose a MALDI-TOF-MS method for identification and relative quantification of FFAs in biological samples of different origins. Our approach relies on formation of monomolecular Langmuir films (LFs) at the interphase of aqueous barium acetate solution, supplemented with low amounts of 2,5-dihydroxybenzoic acid, and hexane extracts of biological samples. This resulted in detection limits of 10–13–10–14 mol and overall method linear dynamic range of at least 4 orders of magnitude with accuracy and precision within 2 and 17%, respectively. The method precision was verified with eight sample series of different taxonomies, which indicates a universal applicability of our approach. Thereby, 31 and 22 FFA signals were annotated by exact mass and identified by tandem MS, respectively. Among 20 FFAs identified in Fucus algae, 14 could be confirmed by gas chromatography-mass spectrometry.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
This article presents new possibilities of using thin films of lanthanide stearates as sorbent materials. Modification of the Q-sense device resonator with monolayers of lanthanide stearates by the ...Langmuir–Schaeffer method made it possible to study the process of insulin protein adsorption on the surface of new thin-film sorbents. The resulting films were also characterized by compression isotherms, chemical analysis, scanning electron microscopy, and mass spectrometry. The transition of stearic acid to salt was recorded by IR spectroscopy. Using the LDI MS method, the main component of thin films, lanthanide distearate, was established. The presence of Eu2+ in thin films was revealed. In the case of europium stearate, the maximum value of insulin adsorption was obtained, −1.67·10−10 mole/cm2. The findings suggest the possibility of using thin films of lanthanide stearates as a sorption material for the proteomics determination of the quantitative protein content in complex fluid systems by specific adsorption on modified surfaces and isolation of such proteins from complex mixtures.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM, UPUK
•Immobilization of Ni2+ ions at the inner surface of monodisperse spherical mesoporous SiO2 particles.•Monodisperse spherical mesoporous SiO2/Ni particles of 500±25nm diameter as metal affinity ...sorbents.•Diclofenac extraction by IMAC technique.•Addition of PFOS to IMAC eluents improves the recovery degree of diclofenac (up to 98%).•The obtained thermodynamics analysis data indicate the chemical nature of the DCF interaction with the surface of the sorbent.
In this research, a novel IMAC sorbent with high specificity for chlorine-containing compounds was developed. Ni-functionalized monodisperse spherical mesoporous silica particles of 500±25nm diameter were synthesized and their metal affinity properties were studied with the use of diclofenac as the model substance. The particles were aggregatively stable in the pH range of 3–12. The sorbent demonstrated a high adsorption capacity (0.60±0.06μg of DCF per 1mg of the sorbent) and high adsorption/desorption rate (20 and 5min was enough for the sorbent saturation and desorption of DCF, correspondingly). A mixture of eluents with addition of PFOS providing the almost complete recovery (98%) of diclofenac was first proposed. The monodispersity and the high sedimentation and aggregative stability of the particles provide the formation of a stable hydrosol even under ultrasound treatment which makes the mSiO2/Ni particles suitable for batch chromatography.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Novel dense and supported (polyacrylonitrile substrate) mixed matrix membranes based on biopolymer sodium alginate (SA), modified by Zr-MOFs were developed to improve pervaporation dehydration ...properties of a parent SA membrane. The following Zr-MOFs were synthesized and tested as modifiers: unmodified UiO-66 and modified UiO-66(NH2)-AcOH and UiO-66(NH2)-EDTA. Two kinds of mixed matrix membranes were developed: without additional treatment and cross-linked with calcium chloride. The synthesized Zr-MOFs nanoparticles and developed SA and SA-Zr-MOFs membranes were studied using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, surface area measurement, atomic force microscopy, X-ray diffraction analysis, thermogravimetric analysis, and swelling experiments. Dense and supported membranes were tested for their transport properties in the pervaporation dehydration of isopropanol (12, 30 wt% water for the untreated membranes and 12–100 wt% water for the cross-linked membranes). The best transport properties (dehydration of water/isopropanol mixtures at 22 °C) were demonstrated by a supported cross-linked membrane, containing 15 wt% of UiO-66: permeation flux 0.47–3.38 kg/(m2h), water content in permeate 99.9-97.5 wt%.
Display omitted
•Synthesis of Zr-MOFs: UiO-66, UiO-66(NH2)-AcOH and UiO-66(NH2)-EDTA was undertaken.•Highly efficient supported cross-linked membranes based on SA/Zr-MOFs were developed.•Modified membranes had higher selectivity and flux compared to unmodified ones.•Membranes had high stability in diluted isopropanol solutions and commercial perspective.•15 wt% UiO-66 was found optimal based on pervaporation isopropanol dehydration data.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Display omitted
A new polymer-analogous transformations of poly(N-vinylpyrrolidone) was used to prepare new complex-forming macromolecular systems containing thiourea and thio-semicarbazone sites. ...Two variants of modification were realized, namely, the method including the preliminary in situ activation of nucleophilic centres of the polymer amide fragments with dimethyl sulfate followed by introducing nucleophilic agents into the system, and the method including partial hydrolysis of poly(N-vinylpyrrolidone) followed by the amide coupling. The obtained modified polymeric materials react with silver ions in aqueous solution.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Display omitted
•MOF particles UiO-66(NH2)-EDTA was synthesized.•Novel polyphenylene isophthalamide (PA)/UiO-66(NH2)-EDTA membranes were developed.•Optimal loading of UiO-66(NH2)-EDTA to PA was ...15 wt%.•Pervaporation separation of azeotropic methanol/toluene mixture was carried out.•Supported PA/15 wt.%MOF membrane on regenerated cellulose possessed flux 1.5 kg/(m2h).
As a rule, the polymeric membranes have low permeability in separation of low molecular weight components. In spite of this fact, the membrane processes have significant advantages compare with conventional technologies, in particular, low energy consumption and environmental friendliness. To improve transport properties of the polymer membrane their modification should be carried out. In the present work, the development of highly methanol-permeable pervaporation membranes based on poly-m-phenylene isophthalamide (PA) is achieved by two strategies: (i) modification of PA by novel synthesized and characterized highly stable metal–organic framework UiO-66(NH2)-EDTA particles and (ii) development of supported membranes with thin selective layer on the regenerated cellulose substrate. First time the composite structure has been simulated: atomistic molecular dynamics simulations demonstrate the partial penetration of polymer inside the modifier and confirms the nature of the interaction between polymer and modifier assessed by spectroscopic methods. The optimal characteristics in respect of industrial use are obtained for supported PA/UiO-66(NH2)-EDTA (15%) membrane: 1.55 kg/(m2h) permeation flux and 93.1 wt% methanol in the permeate for the separation of azeotropic methanol/toluene mixture.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
