Search results for "Spectroscopy"
showing 10 items of 10293 documents
Enrichment of amino acids by supported liquid membrane extraction using Aliquat 336 as a carrier
1998
Abstract The possible application of Aliquat 336 (trioctylmethyl ammonium chloride) as a carrier for liquid membrane extraction of amino acids was investigated. The extraction is performed from an aqueous donor phase with pH > 11 to an acceptor phase containing a salt solution through a supported liquid membrane with Aliquat 336 as a carrier in the membrane to facilitate amino acid transport. Counter-coupled transport of chloride anions from the acceptor phase to the donor phase is the driving force of the mass transfer in this system. The extraction efficiency depends on the donor phase pH, the carrier concentration in the liquid membrane, the composition of the acceptor phase and the hydr…
Photodegradation of Brilliant Green Dye by a Zinc bioMOF and Crystallographic Visualization of Resulting CO2
2021
We present a novel bio-friendly water-stable Zn-based MOF (1), derived from the natural amino acid L-serine, which was able to efficiently photodegrade water solutions of brilliant green dye in only 120 min. The total degradation was followed by UV-Vis spectroscopy and further confirmed by single-crystal X-ray crystallography, revealing the presence of CO2 within its channels. Reusability studies further demonstrate the structural and performance robustness of 1.
Oligomeric State and Holding Activity of Hsp60
2023
Similar to its bacterial homolog GroEL, Hsp60 in oligomeric conformation is known to work as a folding machine, with the assistance of co-chaperonin Hsp10 and ATP. However, recent results have evidenced that Hsp60 can stabilize aggregation-prone molecules in the absence of Hsp10 and ATP by a different, “holding-like” mechanism. Here, we investigated the relationship between the oligomeric conformation of Hsp60 and its ability to inhibit fibrillization of the Ab40 peptide. The monomeric or tetradecameric form of the protein was isolated, and its effect on beta-amyloid aggregation was separately tested. The structural stability of the two forms of Hsp60 was also investigated using differentia…
The complementary structural studies of the double metal cyanide type catalysts for the ring opening polymerization of the oxiranes
2016
Przeprowadzono badania strukturalne katalizatorów dimetalocyjankowych (DMC) z dwoma rodzajami ligandów organicznych. Zaproponowano wyjaśnienie etapów przebiegu krzywych otrzymanych metodą analizy termograwimetrycznej i różnicowej kalorymetrii skaningowej (TG/DSC) badanych katalizatorów. Wykazano obecność kilku stopni związania ligandów w kompleksach DMC. Na podstawie wyników badań z wykorzystaniem absorpcji rentgenowskiej (XAS) stwierdzono, że centrum aktywne katalizatora stanowi atom cynku. W bezpośrednim sąsiedztwie atomów Zn wykryto obecność atomów Cl, natomiast w najbliższych sferach koordynacyjnych atomu Zn nie wykryto atomów tlenu.
Coordination Chemistry of a Bis(Tetrazine) Tweezer: A Case of Host-Guest Behavior with Silver Salts
2021
The carbon-carbon cross-coupling of phenyl s-tetrazine (Tz) units at their ortho-phenyl positions allows the formation of constrained bis(tetrazines) with original tweezer structures. In these compounds, the face-to-face positioning of the central tetrazine cores is reinforced by π-stacking of the electron-poor nitrogen-containing heteroaromatic moieties. The resulting tetra-aromatic structure can be used as a weak coordinating ligand with cationic silver. This coordination generates a set of bis(tetrazine)-silver(I) coordination complexes tolerating a large variety of counter anions of various geometries, namely, PF6−, BF4−, SbF6−, ClO4−, NTf2−, and OTf−. These compounds were characterized…
Effects of the net charge on abundance and stability of supramolecular surfactant aggregates in gas phase
2011
Self-assembling of amphiphilic molecules under electrospray ionization (ESI) conditions is characterized by quite unexpected phenomenology. The noticeable differences with respect to the condensed phase are attributable to the absence of the surfactant-solvent interactions, the presence of net charge in the aggregates, and the strong deviation from equilibrium conditions. Aiming to investigate the effects of the net charge on abundance and stability of supramolecular surfactant aggregates, positively and negatively charged aggregates of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium methane sulfonate (MetS), butane sulfonate (ButS) and octane sulfonate (OctS) have been studied by E…
Extracellular Vesicles and Tumor-Immune Escape: Biological Functions and Clinical Perspectives
2020
The modulation of the immune system is one of the hallmarks of cancer. It is now widely described that cancer cells are able to evade the immune response and thus establish immune tolerance. The exploration of the mechanisms underlying this ability of cancer cells has always attracted the scientific community and is the basis for the development of new promising cancer therapies. Recent evidence has highlighted how extracellular vesicles (EVs) represent a mechanism by which cancer cells promote immune escape by inducing phenotypic changes on different immune cell populations. In this review, we will discuss the recent findings on the role of tumor-derived extracellular vesicles (TEVs) in re…
Oligoamide Foldamers as Helical Chloride Receptors-the Influence of Electron-Withdrawing Substituents on Anion-Binding Interactions.
2019
The anion-binding properties of three closely related oligoamide foldamers were studied using NMR spectroscopy, isothermal titration calorimetry and mass spectrometry, as well as DFT calculations. The 1 H NMR spectra of the foldamers in [D6 ]acetone solution revealed partial preorganization by intramolecular hydrogen bonding, which creates a suitable cavity for anion binding. The limited size of the cavity, however, enabled efficient binding by the inner amide protons only for the chloride anion resulting in the formation of a thermodynamically stable 1:1 complex. All 1:1 chloride complexes displayed a significant favourable contribution of the entropy term. Most likely, this is due to the …
TiO2 Nanostructures for Photoelectrocatalytic Degradation of Acetaminophen
2019
[EN] Advanced oxidation processes driven by renewable energy sources are gaining attention in degrading organic pollutants in waste waters in an efficient and sustainable way. The present work is focused on a study of TiO2 nanotubes as photocatalysts for photoelectrocatalytic (PEC) degradation of acetaminophen (AMP) at different pH (3, 7, and 9). In particular, different TiO2 photocatalysts were synthetized by stirring the electrode at different Reynolds numbers (Res) during electrochemical anodization. The morphology of the photocatalysts and their crystalline structure were evaluated by field emission scanning electron microscopy (FESEM) and Raman confocal laser microscopy (RCLM). These a…
Raman spectral identification of phase distribution in anodic titanium dioxide coating
2017
Growing need for cleaner environment and energy production has brought about a hunt for perspective materials. One of such perspective materials is titanium dioxide (TiO2, titania) due to its chemical stability and photocatalytic properties. Titania can be synthesized through many methods but anodization process is one of the prevailing methods to produce high active surface nanostructured titania. Various anodization electrolytes produce different polymorphs of TiO2. Uniform phase distribution on the surface is crucial for higher photocatalytic activity. In this research, the influence of two electrolytes on polymorph phase distribution of TiO2 was investigated. Phase distribution correlat…