Estimation of the EMI Filter Circuitry from the Insertion Loss Characteristics

The paper deals with the EMI filter models for the calculation of the insertion loss characteristics. The insertion loss is in fact the basic EMI filter property. Unfortunately it is not easy to precisely define and measure this parameter in a wide frequency range due to variability of terminating impedances. The uncertainty of the potential impedance termination really complicates the measurements and also comparison of the performance of filters. A model with spurious components is introduced in this paper. The procedure model design is also added up. The spurious components make together with the real ones form resonant circuits. The resonance frequencies make breakages in the insertion loss characteristic. Their resonance frequencies were identified by the analysis of equivalent circuits of the filter for different measuring systems. The calculation of the values of spurious components, based on knowledge of resonance frequencies, is mentioned at the end of the paper

Lewis Acidic Aluminosilicates: Synthesis, ²⁷Al MQ/MAS NMR, and DFT-Calculated ²⁷Al NMR Parameters

Porous aluminosilicates are functional materials of paramount importance as Lewis acid catalysts in the synthetic industry, yet the participating aluminum species remain poorly studied. Herein, a series of model aluminosilicate networks containing [L–AlO3] (L = THF, Et3N, pyridine, triethylphosphine oxide (TEPO)) and [AlO4]− centers were prepared through nonhydrolytic sol–gel condensation reactions of the spherosilicate building block (Me3Sn)8Si8O20 with L–AlX3 (X = Cl, Me, Et) and [Me4N] [AlCl4] compounds in THF or toluene. The substoichiometric dosage of the Al precursors ensured complete condensation and uniform incorporation, with the bulky spherosilicate forcing a separation between neighboring aluminum centers. The materials were characterized by 1H, 13C, 27Al, 29Si, and 31P MAS NMR and FTIR spectroscopies, ICP-OES, gravimetry, and N2 adsorption porosimetry. The resulting aluminum centers were resolved by 27Al TQ/MAS NMR techniques and assigned based on their spectroscopic parameters obtained by peak fitting (δiso, CQ, η) and their correspondence to the values calculated on model structures by DFT methods. A clear correlation between the decrease in the symmetry of the Al centers and the increase of the observed CQ was established with values spanning from 4.4 MHz for distorted [AlO4]− to 15.1 MHz for [THF–AlO3]. Products containing exclusively [TEPO–AlO3] or [AlO4]− centers could be obtained (single-site materials). For L = THF, Et3N, and pyridine, the [AlO4]− centers were formed together with the expected [L–AlO3] species, and a viable mechanism for the unexpected emergence of [AlO4]− was proposed

Pentamethinium salts suppress key metastatic processes by regulating mitochondrial function and inhibiting dihydroorotate dehydrogenase respiration

Mitochondria generate energy and building blocks required for cellular growth and function. The notion that mitochondria are not involved in the cancer growth has been challenged in recent years together with the emerging idea of mitochondria as a promising therapeutic target for oncologic diseases. Pentamethinium salts, cyan dyes with positively charged nitrogen on the benzothiazole or indole part of the molecule, were originally designed as mitochondrial probes. In this study, we show that pentamethinium salts have a strong effect on mitochondria, suppressing cancer cell proliferation and migration. This is likely linked to the strong inhibitory effect of the salts on dihydroorotate dehydrogenase (DHODH)-dependent respiration that has a key role in the de novo pyrimidine synthesis pathway. We also show that pentamethinium salts cause oxidative stress, redistribution of mitochondria, and a decrease in mitochondria mass. In conclusion, pentamethinium salts present novel anti-cancer agents worthy of further studies.SCOPUS: ar.jinfo:eu-repo/semantics/publishe