Підвищення ефективності сепарації пилу у вихрових апаратах із зустрічними закрученими потоками із циліндричною сепараційною камерою (ВАЗЗПЦ) для підприємств хімічних та будівельних матеріалів

Актуальною проблемою, яка постає сьогодні перед вітчизняною промисловістю, є вдосконалення техніки і технології охорони навколишнього середовища в цілому, і, зокрема, зменшення рівня запиленості атмосферного повітря.Вирішення проблеми міститься у процесі сепарації пилу у ВАЗЗПЦ і безперервним вивантаженням уловлюваного пилу стосовно хімічних та будівельних матеріалів

Amphiphilic Stilbene Derivatives Attenuate the Neurotoxicity of Soluble Aβ42 Oligomers by Controlling Their Interactions with Cell Membranes

Misfolded proteins or polypeptides commonly observed in neurodegenerative diseases, including Alzheimer’s disease (AD), are promising drug targets for developing therapeutic agents. To target the amyloid-β (Aβ) plaques and oligomers, the hallmarks of AD, we have developed twelve amphiphilic small molecules with different hydrophobic and hydrophilic fragments. In vitro binding experiments (i.e., fluorescence saturation assays) demonstrated that these amphiphilic compounds show high binding affinity to both Aβ plaques and oligomers, and six of them exhibit even higher binding affinity toward Aβ oligomers. These amphiphilic compounds can also label ex vivo Aβ species in the brain sections of transgenic AD mice, as shown by immunostaining with an Aβ antibody. Molecular docking studies were performed to help understand the structure-affinity relationships. To our delight, four amphiphilic compounds can alleviate Cu2+-Aβ induced toxicity in mouse neuroblastoma N2a via cell toxicity assays. In addition, confocal fluorescence imaging studies provided evidence that compounds ZY-15-MT and ZY-15-OMe can disrupt the interactions between Aβ oligomers and human neuroblastoma SH-SY5Y cell membranes. Overall, these studies suggest that developing compounds with amphiphilic properties that target Aβ oligomers can be an effective strategy for small molecule AD therapeutics.</p

Electrocatalytic O2 Reduction by an Organometallic Pd(III) Complex via a Binuclear Pd(III) Intermediate

The development of electrocatalysts for the selective O2-to-H2O conversion, the O2 reduction reaction (ORR), is of great interest for improving the performance of fuel cells. In this context, molecular catalysts that are known to mediate the 4H+/4e– reduction of O2 to H2O tend to be marred by limited stability and selectivity in controlling the multi-proton and multi-electron transfer steps. Thus, evaluation of new transition metal complexes, including organometallic species, for ORR reactivity could uncover new molecular catalysts with improved properties. We have previously reported the synthesis and characterization of various organometallic PdIII complexes stabilized by the tetradentate ligand N,N′-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane (tBuN4). These complexes were shown to react with O2 and undergo oxidatively-induced C–C and C–heteroatom bond formation reactions in the presence of O2. These O2-induced oxidative transformations prompted us to evaluate the ORR reactivity of such organometallic Pd complexes, which to the best of our knowledge has never been studied before for any molecular Pd catalyst. Herein, we report the ORR reactivity of the [(tBuN4)PdIIIMeCl]+ complex, under both homogeneous and heterogeneous conditions in a non-aqueous and acidic aqueous electrolyte, respectively. Cyclic voltammetry and hydrodynamic electrochemical studies for [(tBuN4)PdIIIMeCl]+ revealed the electrocatalytic reduction of O2 to H2O proceeds with Faradaic efficiencies (FE) of 50-70% in the presence of acetic acid (AcOH) in MeCN. The selectivity toward H2O production further improved to a FE of 80-90% in an acidic aqueous medium (pH 0), upon immobilization of the molecular catalyst onto edge plane graphite (EPG) electrodes. Analysis of electrochemical data suggests the formation of a binuclear PdIII intermediate in solution, likely a PdIII-peroxo-PdIII species, which dictates the thermochemistry of the ORR process for [(tBuN4)PdIIIMeCl]+ in MeCN, and thus being a rare example of a bimolecular ORR process. The maximum second-order turnover frequency TOFmax(2) = 2.76 x 108 M–1 sec–1 was determined for 0.32 mM of [(tBuN4)PdIIIMeCl]+ in the presence of 1 M AcOH in O2-saturated MeCN with an overpotential of 0.32 V. By comparison, a comparatively lower TOFmax(2) = 1.25 x 105 M–1 sec–1 at a higher overpotential of 0.8 V was observed for [(tBuN4)PdIIIMeCl]PF6 adsorbed onto EPG electrodes in O2-saturated 1 M H2SO4 aqueous solution. Overall, reported herein is a detailed ORR reactivity study using a novel PdIII organometallic complex and benchmark its selectivity and energetics toward O2 reduction in MeCN and acidic aqueous solutions. </p

Cu-Based Turn-on Fluorescent Sensors for Cu-rich Amyloid β Aggregates

Protein misfolding and metal dishomeostasis are two keypathological factors of Alzheimer’s disease. Previous studies have showed that Cu‐mediated Aβ aggregation pathways lead to formation of neurotoxic Aβ oligomers. Herein, we reported a series of picolinic acid‐based Cu‐activatable sensors, which can be used for the fluorescence imaging of Cu‐rich Aβ aggregates.</div

Kinetic Analysis of Iron-Dependent Histone Demethylases: α‑Ketoglutarate Substrate Inhibition and Potential Relevance to the Regulation of Histone Demethylation in Cancer Cells

The Jumonji C domain-containing histone demethylases (JmjC-HDMs) are α-ketoglutarate (αKG)-dependent, O₂-activating, non-heme iron enzymes that play an important role in epigenetics. Reported herein is a detailed kinetic analysis of three JmjC-HDMs, including the cancer-relevant JMJD2C, that was achieved by employing three enzyme activity assays. A continuous O₂ consumption assay reveals that HDMs have low affinities for O₂, suggesting that these enzymes can act as oxygen sensors in vivo. An interesting case of αKG substrate inhibition was found, and the kinetic data suggest that αKG inhibits JMJD2C competitively with respect to O₂. JMJD2C displays an optimal activity in vitro at αKG concentrations similar to those found in cancer cells, with implications for the regulation of histone demethylation activity in cancer versus normal cells

Detection and Characterization of Mononuclear Pd(I) Complexes

Palladium is a versatile transition metal used to catalyze a large number of chemical transformations, largely due to its ability to access various oxidation states (0, I, II, III, and IV). Among these oxidation states, Pd(I) is arguably the least studied, and while dinuclear Pd(I) complexes are more common, mononuclear Pd(I) species are very rare. Reported herein are spectroscopic studies of a series of Pd(I) intermediates generated by the chemical reduction of Pd(II) precursors supported by the tetradentate ligands 2,11-dithia[3.3](2,6)pyridinophane (N2S2) and N,N’-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane (tBuN4): [(N2S2)PdII(MeCN)]2(OTf)4 (1), [(N2S2)PdIIMe]2(OTf)2 (2), [(N2S2)PdIICl](OTf) (3), [(N2S2)PdIIX](OTf)2 (X = tBuNC 4, PPh3 5), [(N2S2)PdIIMe(PPh3)](OTf) (6), and [(tBuN4)PdIIX2](OTf)2 (X = MeCN 8, tBuNC 9). In addition, a stable Pd(I) dinuclear species, [(N2S2)PdI(m-tBuNC)]2(ClO4)2 (7), was isolated upon the electrochemical reduction of 4 and structurally characterized. Moreover, the (tBuN4)PdI intermediates, formed from the chemical reduction of [(tBuN4)PdIIX2](OTf)2 (X = MeCN 8, tBuNC 9) complexes, were investigated by EPR spectroscopy, X-ray absorption spectroscopy (XAS), and DFT calculations, and compared with the analogous (N2S2)PdI systems. Upon probing the stability of Pd(I) species under various ligand environments (N2S2 and tBuN4), it is apparent that the presence of soft ligands such as tBuNC and PPh3 significantly improves the stability of Pd(I) species, which should make the isolation of mononuclear Pd(I) species possible.</p

Improved Oxidative C-C Bond Formation Reactivity of High-Valent Pd Complexes Supported by a Pseudo-Tridentate Ligand

There is a large interest in developing oxidative transformations catalyzed by palladium complexes that employ environmentally friendly and economical oxidizing reagents such as dioxygen. Recently, we have reported the isolation and characterization of various mononuclear PdIII and PdIV complexes supported by the tetradentate ligands N,N’-di-alkyl-butyl-2,11-diaza[3.3](2,6)pyridinophane (RN4, R = tBu, iPr, Me), and the aerobically-induced C-C and C-heteroatom bond formation reactivity was investigated in detail. Given that the steric and electronic properties of the multidentate ligands were shown to tune the stability and reactivity of the corresponding high-valent Pd complexes, herein we report the use of an asymmetric N4 ligand, N-mehtyl-N’-tosyl-2,11-diaza[3.3](2,6)pyridinophane (TsMeN4), in which one amine N atom contains a tosyl group. The N-Ts donor atom exhibits a markedly reduced donating ability, which led to the formation of transiently stable PdIII and PdIV complexes, and consequently the corresponding O2 oxidation reactivity and the subsequent C-C bond formation was improved significantly.</p

Isolation and Catalytic Reactivity of Mononuclear Palladium(I) Complexes

Palladium complexes are among the most commonly used transition metal catalysts for different organic transformations with wide applications in the chemical synthesis. Currently, catalytic transformations involving Pd(0)/Pd(II) catalytic cycles are very well-known, and processes involving Pd(II)/Pd(III)/Pd(IV) intermediates are also gaining interest in recent years due to the increasing relevance of high-valent Pd species. By contrast, isolated low-valent Pd(I) complexes, especially mononuclear Pd(I) species, are very rare. Herein, we report the isolation of two heteroleptic Pd(I) complexes stabilized by dithiapyridinophane ligands that were fully characterized by single-crystal X-ray diffraction, EPR, IR, and UV-Vis spectroscopies, and computational studies. Excitingly, these Pd(I) complexes are shown to be superior catalysts for the Csp2-Csp3 Kumada cross-coupling reaction vs. their Pd(0) or Pd(II) analogs.</p