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Viktoria V. Sursyakova Vladimir A. Levdansky Anatoly I. Rubaylo 《Electrophoresis》2019,40(12-13):1656-1661
The complexation of betulinic and betulonic acids (BIA and BOA) (pentacyclic lupane triterpenoids) with (2‐hydroxypropyl)‐γ‐cyclodextrin (HP‐γ‐CD) was studied at different temperatures using the method combining phase‐solubility technique and CZE. In contrast to mobility shift ACE utilizing the electrophoretic mobility, in this approach, the peak areas are used. The apparent binding (stability, formation) constants are obtained by the Higuchi and Connors method from the linear segment of compound solubility diagrams in CD solutions. It was found that the apparent binding constants of the HP‐γ‐CD complexes of BIA and BOA decrease with increasing temperature. The binding constants of BOA complexes are slightly higher than those of BIA complexes; this can be explained by difference in the hydration degrees of carbonyl and hydroxyl groups. On the basis of the binding constants obtained and their temperature dependences (van't Hoff plot), the enthalpy as well as entropy changes and Gibbs free energies were calculated. It was found that the complexation was characterized by negative changes of enthalpy and entropy, that is, it was controlled by enthalpy changes. The results obtained can be used for the optimization of microcapsulation processes of BOA and BIA with the HP‐γ‐CD application in order to increase solubility and bioavailability of these compounds. 相似文献
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Nonlinear Dynamics - We first present a brief review of nonlinear asset-pricing models and contributions in which such models have been used as benchmarks to evaluate the effectiveness of a number... 相似文献
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Britta Schmitt Boris N. Khoromskij Venera Khoromskaia Volker Schulz 《Numerical Linear Algebra with Applications》2022,29(1):e2404
We introduce the tensor numerical method for solving optimal control problems that are constrained by fractional two- (2D) and three-dimensional (3D) elliptic operators with variable coefficients. We solve the governing equation for the control function which includes a sum of the fractional operator and its inverse, both discretized over large 3D spacial grids. Using the diagonalization of the arising matrix-valued functions in the eigenbasis of the one-dimensional Sturm–Liouville operators, we construct the rank-structured tensor approximation with controllable precision for the discretized fractional elliptic operators and the respective preconditioner. The right-hand side in the constraining equation (the optimal design function) is supposed to be represented in a form of a low-rank canonical tensor. Then the equation for the control function is solved in a tensor structured format by using preconditioned CG iteration with the adaptive rank truncation procedure that also ensures the accuracy of calculations, given an -threshold. This method reduces the numerical cost for solving the control problem to (plus the quadratic term with a small weight), which outperforms traditional approaches with complexity in the 3D case. The storage for the representation of all 3D nonlocal operators and functions involved is also estimated by . This essentially outperforms the traditional methods operating with fully populated matrices and vectors in . Numerical tests for 2D/3D control problems indicate the almost linear complexity scaling of the rank truncated preconditioned conjugate gradient iteration in the univariate grid size n. 相似文献
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In this article, capillary electrophoresis was used to measure the effective electrophoretic mobility of ester betulin derivatives as a pH function and to study their complexation with γ-cyclodextrin (γ-CD). The electrophoretic mobility of betulin 3,28-diphthalate (DPhB) and 3,28-disuccinate (DScB) changed unusually with decreasing pH: instead of decreasing, it first increased and then decreased. This fact as well as the turbidity of sample solutions at pH from 2.5 to 6, broadening of electrophoretic peaks and a decrease in the surface tension of the solutions indicates that these betulin derivatives, being amphiphilic compounds and weak acids, exist as micelles in aqueous solutions at pH 6 and below. The inclusion complexation of betulin derivatives with γ-CD at pH 9.18 and 4.5 was studied by mobility shift affinity capillary electrophoresis. At pH 9.18, the apparent binding (stability) constant logarithms for 1:1 γ-CD complexes of DPhB, betulin 3,28-disulfate (DSB) and DScB with 95% confidence interval limits were equal to 7.44 ± 0.02, 7.09 (7.01–7.19), and 6.97 (6.87–7.08) at 25°C, respectively. At pH 4.5, the binding constant for the DSB complex was slightly lower, while the micelle formation did not allow determining the exact values of the constants for the DPhB and DScB complexes. 相似文献
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Yihui Yan Lucas Schmitt Anastasiya Khramchenkova Jozef Lengyel 《Journal of mass spectrometry : JMS》2023,58(7):e4955
We present the design and performance of an in-house built electrospray ionization-mass spectrometry (ESI-MS) interface equipped with an S-lens ion guide. The ion source was designed specifically for our ion beam experiments to investigate the chemical reactivity and deposition of the clusters and nanoparticles. It includes standard ESI-MS interface components, such as nanoelectrospray, ion transfer capillary, and the S-lens. A custom design enables systematic optimization of all relevant factors influencing ion formation and transfer through the interface. By varying the ESI voltage and flow rate, we determined the optimal operating conditions for selected silica emitters. A comparison of the pulled silica emitters with different tip inner diameters reveals that the total ion current is highest for the largest tip, whereas a tip with the smallest diameter exhibited the highest transmission efficiency through the ESI-MS interface. Ion transmission through the transfer capillary is strongly limited by its length, but the loss of ions can be reduced by increasing the capillary voltage and temperature. The S-lens was characterized over a wide range of RF frequencies and amplitudes. Maximum ion current was detected at RF amplitudes greater than 50 V peak-to-peak (p/p) and frequencies above 750 kHz, with a stable ion transmission region of about 20%. A factor of 2.6 increase in total ion current is observed for 650 kHz as RF amplitudes reach 400 V p/p. Higher RF amplitudes also focus the ions into a narrow beam, which mitigates their losses when passing through the ion guide. 相似文献
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David Terrey Jack James Ivan Tankovski Monika Dalim Michel van Spankeren Arpita Chakraborty Eric Schmitt Aman Paul 《Molecules (Basel, Switzerland)》2021,26(6)
Marine feed ingredients derived from cephalopods (e.g., squid) and crustaceans (e.g., krill) are commercially used to improve the palatability of shrimp diets. Increase in global demand for shrimps has resulted in overfishing of these marine organisms and is a matter of concern. Insect protein hydrolysate could be a sustainable alternative for the possible replacement of these marine feed ingredients. During this study, four formulations: diet A (control: not containing any palatability enhancer), diet B (containing squid meal and krill oil), diet C (containing 1% insect protein hydrolysate), and diet D (containing 2% insect protein hydrolysate) were tested for (1) time required by first subject to begin feeding (time to strike) and (2) palatability in Litopenaeus vannamei. Additionally, the chemical composition of all four diet formulations was also analyzed. Results indicate that all diets had similar crude composition. The major essential amino acids in all diets were leucine and lysine, whereas eicosapentaenoic acid was the major omega-3 fatty acid in all diets. There were no significant differences between the mean time to strike for all the tested formulations. Palatability of tested formulations was found in the following order: diet D > diet C > diet B = diet A (p < 0.05), indicating that addition of squid meal and krill oil has no effect on palatability in comparison to control, whereas inclusion of insect protein hydrolysates significantly improves the palatability of formulations. Palatability enhancement potential of insect protein hydrolysate could be attributed to the high free amino acid content and water solubility in comparison to squid meal. 相似文献
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