Kuredegn7433

Soft ionization by a chemical reaction in transfer (SICRIT) is applied to couple gas chromatography (GC) to a high-resolution atmospheric pressure inlet mass spectrometer. These instruments are generally used in combination with liquid chromatography systems (LC-MS). Ionization of alkanes is not possible here with conventional electrospray ionization. Alternatively, separate GC-electron ionization (EI)-MS is employed for the analysis of nonpolar substances like alkanes, however, with the inherent challenge of strong fragmentation. In the case of alkanes, the determination of molecular masses becomes nearly impossible in complex hydrocarbon mixtures because of the wealth of similar fragment ions and the absence of the molecular ion signal. SICRIT, a soft ionization technique based on dielectric barrier discharge (DBDI), produces characteristic oxidized cations from alkanes that can be directly correlated to their molecular mass. Isotope labeling experiments reveal an ionization mechanism via hydride abstraction and reaction with water. Soft ionization can be achieved for iso- and n-alkanes, with very little fragmentation, enabling the determination of their molecular mass. Calibrations for n-alkanes from C10 to C30 were performed exhibiting high linearity, reproducibility, and sensitivity with an average LOD of 69 pg (on column). Measurements of diesel fuel samples are compared to traditional GC-EI-MS. The presented method combines sensitivity and easy handling of a GC-EI-MS with the determination of molecular mass commonly only achieved with field ionization (FI)-MS, while using existing and highly optimized mass spectrometers commonly coupled with LC. Additionally, many other analytes such as (alkylated-) PAHs could be detected simultaneously in the diesel sample.A visible-light-enabled, photocatalyst-free conjugate addition reaction of dehydroamino acids is disclosed. Employing 4-acyl-1,4-dihydropyridines as both a radical reservoir and reductant, various β-acyl α-amino acids and their deuterated analogues were obtained in good results. Both late-stage peptide modification and stereoselective synthesis of chiral oxazolidinones are successfully achieved. The protocol is characterized by mild conditions and efficient derivatization, thus unlocking a novel blueprint to access unnatural amino acid derivatives, important building blocks with potential application in the peptidomimetic toolbox.Protein patterning has emerged as a powerful means to interrogate adhering cells. However, the tools to apply a sub-micrometer periodic stimulus and the analysis of the response are still being standardized. We propose a technique combining electron beam lithography and surface functionalization to fabricate nanopatterns compatible with advanced imaging. The repetitive pattern enables a deep-learning algorithm to reveal that T cells organize their membrane and actin network differently depending upon whether the ligands are clustered or homogeneously distributed, an effect invisible to the unassisted human eye even after extensive image analysis. This fabrication and analysis toolbox should be useful, both together and separately, for exploring general correlation between a spatially structured subcellular stimulation and a subtle cellular response.Readily available from esters or ketones, cyclopropanols are inclined to undergo diverse ring-opening transformations. Their one-electron oxidation is a conventional way to β-carbonyl radicals. However, despite this fact, their application as a coupling partner in dual photoredox and nickel-catalyzed reactions with organic halides remains underdeveloped. Here, we report that the Ti(OiPr)4 additive enables this elusive cross-coupling with aryl and alkenyl bromides leading to β-substituted ketones.The interactions of mono-rhamnolipids (mono-RLs) with model membranes were investigated through a biomimetic approach using phospholipid-based liposomes immobilized on a gold substrate and also by the multiparametric surface plasmon resonance (MP-SPR) technique. Biotinylated liposomes were bound onto an SPR gold chip surface coated with a streptavidin layer. The resulting MP-SPR signal proved the efficient binding of the liposomes. The thickness of the liposome layer calculated by modeling the MP-SPR signal was about 80 nm, which matched the average diameter of the liposomes. The mono-RL binding to the film of the phospholipid liposomes was monitored by SPR and the morphological changes of the liposome layer were assessed by modeling the SPR signal. We demonstrated the capacity of the MP-SPR technique to characterize the different steps of the liposome architecture evolution, i.e., from a monolayer of phospholipid liposomes to a single phospholipid bilayer induced by the interaction with mono-RLs. Further washing treatment with Triton X-100 detergent left a monolayer of phospholipid on the surface. As a possible practical application, our method based on a biomimetic membrane coupled to an SPR measurement proved to be a robust and sensitive analytical tool for the detection of mono-RLs with a limit of detection of 2 μg mL-1.Classical ion mobility spectrometers (IMS) operated at ambient pressure, often use atmospheric pressure chemical ionization (APCI) sources to ionize organic compounds. In APCI, reactant ions ionize neutral analyte molecules via gas-phase ion-molecule reactions. The positively charged reactant ions in purified, dry air are H3O+, NO+, and O2+•. However, the hydration of reactant ions in classical IMS operated at ambient pressure renders ionization of certain analytes difficult. In contrast to classical IMS operated at ambient pressure, High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) are operated at a decreased pressure of 10-40 mbar, allowing operation at high reduced electric field strengths of up to 120 Td. At such high reduced field strengths, ions reach high effective temperatures causing collision-induced cluster dissociation of the hydrated gas-phase ions, allowing ionization of nonpolar and low proton affinity analytes. The reactant ion population, consisting of H3O+(H2O)n, NO+(H2O)m, and O2+•(H2O)p with an individual abundance that strongly depends on the reduced field strength, differs from the reactant ion population in IMS operated at ambient pressure, which affects the ionization of analyte molecules. In this work, we investigate the influence of reduced field strength on the product ion formation of aromatic hydrocarbons used as model substances. A HiKE-IMS-MS coupling was used to identify the detected ion species. The results show that the analytes form parent cations via charge transfer with NO+(H2O)m and O2+•(H2O)p depending on ionization energy and protonated parent molecules via proton transfer and ligand switching with H3O+(H2O)n mainly depending on proton affinity.In the effort to discover new targets and improve the therapeutic efficacy of metal-containing anticancer compounds, transition metal complexes that can elicit cytotoxicity when irradiated with light of a proper wavelength and, then, candidates as potential photosensitizers for photodynamic therapy are actively being investigated. In this work, the cytotoxicity in the dark and the photophysical properties of the complex Pt(N∧C∧N)Cl, where the N∧C∧N ligand is 2,6-dipyrido-4-methyl-benzene chloride, are investigated in detail by means of a series of theoretical levels, that is density functional theory and its time-dependent extension together with molecular dynamics (MD) simulations. In the dark, cytotoxicity has been explored by simulating the steps of the mechanism of action of classical Pt(II) complexes. The suitability of the investigated complex to act as a photosensitizer has been verified by calculating spectroscopic properties for both the unperturbed complex and its aquated and guanine-bound forms. Furthermore, using MD simulation outcomes as a starting point, the photophysical properties of DNA-intercalated and -bound complexes have been evaluated with the goal of establishing how intercalation and binding affect sensitization activity.We report the synthesis of quinolines using cyclopropenes and an azidobenziodazolone (ABZ) hypervalent iodine reagent as an azide radical source under visible-light irradiation. Multisubstituted quinoline products were obtained in 34-81% yield. The reaction was most efficient for 3-trifluoromethylcyclopropenes, affording valuable 4-trifluoromethylquinolines. The transformation probably proceeds through the cyclization of an iminyl radical formed by the addition of the azide radical on the cyclopropene double bond, followed by ring-opening and fragmentation.Propiconazole (PCZ) is a hepatotoxic triazole fungicide. There are insufficient data on how PCZ induces liver fibrosis in humans. This study aimed to investigate the effect of PCZ on liver fibrosis and its underlying mechanisms. HepG2 cells and Sprague-Dawley rats were exposed to PCZ at doses of 0-160 μM (3-72 h) and 0.5-50 mg/kg body weight/day (28 days), respectively. PCZ-treated cells activated intracellular oxidative stress via cytochrome P450 and had higher mRNA levels of interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase (MMP)-2, MMP-9, and transforming growth factor-β (TGF-β) than the control. PCZ treatment in cells induced a morphological transition with E-cadherin decrease and vimentin and Snail increase via the oxidative stress and TGF-β/Smad pathways. PCZ administration in rats induced liver fibrosis through pathological changes, epithelial-mesenchymal transition, and collagen deposition. Thus, our data suggest that exposure of PCZ to humans may be a risk factor for the functional integrity of the liver.Recent DFT based molecular engineering to obtain stable oxathiirane S-oxide derivatives evokes the recommencement of the use of carbenes for the sequestering of SO2, which has been kept separate so far. Carbene is one of the key chemicals for the sequestering of various premier greenhouse gases like CO2, CO, N2O, etc. In this respect, a comparative study of the reactivity of carbenes with variant greenhouse gases is highly demanding. The present investigation is engrossed in the comparative reactivity of SO2 and NO2 with carbenes. All three selected carbenes are highly susceptible to SO2 and NO2. Through an immaculate mechanistic study, we are able to corroborate that the end product of the carbene-SO2 reaction is an adduct which has a preferable structure having a six-membered ring with hydrogen bonding instead of ketone and SO with higher thermodynamic stability than the corresponding oxathiirane S-oxide derivative. Carbene reacts with NO2 to form a stable carbene N, N-dioxide derivative which forms vibrationally excited oxaziridine N-oxide which rapidly dissociates to form a ketone derivative. The formation of carbene S, S-dioxide and carbene N, N-dioxide is a barrierless process. The dissociation of oxaziridene N-oxide is also a barrierless process.Water contamination is a global threat due to its damaging effects on the environment and human health. Water pollution by microplastics (MPs), dissolved natural organic matter (NOM), and other turbid particles is ubiquitous in water treatment. Here, we introduce lysozyme amyloid fibrils as a novel natural bio-flocculant and explore their ability to flocculate and precipitate the abovementioned undesired colloidal objects. Thanks to their positively charged surface in a very broad range of pH, lysozyme amyloid fibrils show an excellent turbidity removal efficiency of 98.2 and 97.9% for dispersed polystyrene MPs and humic acid (HA), respectively. Additionally, total organic carbon measurements confirm these results by exhibiting removal efficiencies of 93.4 and 61.9% for purifying water from dispersed MPs and dissolved HA, respectively. The comparison among amyloid fibrils, commercial flocculants (FeCl3 and polyaluminumchloride), and native lysozyme monomers points to the superiority of amyloid fibrils at the same dosage and sedimentation time.