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731.
Letícia S. Contieri Leonardo M de Souza Mesquita Vitor L. Sanches Juliane Viganó Renan Canute Kamikawachi Wagner Vilegas Mauricio A. Rostagno 《Journal of separation science》2023,46(3):2200440
Propolis is a bee product with a complex chemical composition formed by several species from different geographical origins. The complex propolis composition requires an accurate and reproducible characterization of samples to standardize the quality of the material sold to consumers. This work developed an ultra-high-performance liquid chromatography with a photodiode array detector method to analyze propolis phenolic compounds based on the two key propolis biomarkers, Artepillin C and p-Coumaric acid. This choice was made due to the complexity of the sample with the presence of several compounds. The optimized method was hyphenated with mass spectrometry detection allowing the detection of 23 different compounds. A step-by-step strategy was used to optimize temperature, flow rate, mobile phase composition, and re-equilibration time. Reverse-phase separation was achieved with a C18 fused-core column packed with the commercially available smallest particles (1.3 nm). Using a fused-core column with ultra-high-performance liquid chromatography allows highly efficient, sensitive, accurate, and reproducible determination of compounds extracted from propolis with an outstanding sample throughput and resolution. Optimized conditions permitted the separation of the compounds in 5.50 min with a total analysis time (sample-to-sample) of 6.50 min. 相似文献
732.
Xabier Telleria-Allika Jesus M. Ugalde Eduard Matito Eloy Ramos-Cordoba Mauricio Rodríguez-Mayorga Xabier Lopez 《International journal of quantum chemistry》2023,123(3):e27019
Singlet and triplet spin state energies for three-dimensional Hooke atoms, that is, electrons in a quadratic confinement, with even number of electrons (2, 4, 6, 8, 10) is discussed using Full-CI and CASSCF type wavefunctions with a variety of basis sets and considering perturbative corrections up to second order. The effect of the screening of the electron–electron interaction is also discussed by using a Yukawa-type potential with different values of the Yukawa screening parameter (λee = 0.2, 0.4, 0.6, 0.8, 1.0). Our results show that the singlet state is the ground state for two and eight electron Hooke atoms, whereas the triplet is the ground spin state for 4-, 6-, and 10-electron systems. This suggests the following Aufbau structure 1s < 1p < 1d with singlet ground spin states for systems in which the generation of the triplet implies an inter-shell one-electron promotion, and triplet ground states in cases when there is a partial filling of electrons of a given shell. It is also observed that the screening of electron–electron interactions has a sizable quantitative effect on the relative energies of both spin states, specially in the case of two- and eight-electron systems, favoring the singlet state over the triplet. However, the screening of the electron–electron interaction does not provoke a change in the nature of the ground spin state of these systems. By analyzing the different components of the energy, we have gained a deeper understanding of the effects of the kinetic, confinement and electron–electron interaction components of the energy. 相似文献
733.
Grace W. Muna Emily Barrera Lucas Robinson Hiba Majeed Keon Jones Abigail Damschroder Andrew Vila 《Electroanalysis》2023,35(8):e202300019
This work reports on the electroanalytical performance of a glassy carbon electrode (GCE) modified with antimony and bismuth (Sb/Bi-GCE) in detecting heavy metal ions using lead and cadmium as model analytes. The electroanalytical performance of the Sb/Bi-GCE surface was compared to the bismuth modified glassy carbon electrode (Bi-GCE) as well as the antimony modified glassy carbon electrode (Sb-GCE). The Sb/Bi-GCE exhibited excellent figures of merit compared to Bi-GCE and Sb-GCE surfaces. For example, the limit of detection for lead was 0.01 ppb using Sb/Bi-GCE and 0.1 and 1 ppb on Bi-GCE and Sb-GCE, respectively. 相似文献
734.
Francisco J. Ariza-López Domingo Barrera Salah Eddargani María José Ibáñez Juan F. Reinoso 《Mathematical Methods in the Applied Sciences》2023,46(2):1687-1698
A nonstandard low-cost spline approximation method for approximating bivariate functions is constructed. It is applied for Digital Elevation approximation and then its accuracy in the downscaling process is studied. 相似文献