Zusammenfassung Es wurde die Reaktion des Kaliumhypophosphits mit Essigsäureanhydrid untersucht. Neben schon früher beschriebenen Stoffen wurde aus dem Reaktionsprodukt das bisher nicht bekannte Kalium-acetylhypophosphit isoliert. Analog wurden die Kaliumsalze von Propionyl- und Butyrylhypophosphit hergestellt. 相似文献
The analysis of ionic content of exhaled breath condensate (EBC) from one single breath by CE with C4D is demonstrated for the first time. A miniature sampler made from a 2‐mL syringe and an aluminum cooling cylinder for collection of EBC was developed. Various parameters of the sampler that influence its collection efficiency, repeatability, and effect of respiratory patterns were studied in detail. Efficient procedures for the cleanup of the miniature sampler were also developed and resulted in significant improvement of sampling repeatability. Analysis of EBC was performed by CE‐C4D in a 60 mM MES/l ‐histidine BGE with 30 μM CTAB and 2 mM 18‐crown‐6 at pH 6 and excellent repeatability of migration times (RSD < 1.3% (n = 7)) and peak areas (RSD < 7% (n = 7)) of 12 inorganic anions, cations, and organic acids was obtained. It has been shown that the breathing pattern has a significant impact on the concentration of the analytes in the collected EBC. As the ventilatory pattern can be easily controlled during single exhalation, the developed collection system and method provides a highly reproducible and fast way of collecting EBC with applicability in point‐of‐care diagnostics. 相似文献
The ability to simulate the 3D structure of a human body is essential to increase the efficiency of drug development. In vivo conditions are significantly different in comparison to in vitro conditions. A standardly used cell monolayer on tissue culture plastic (2D cell culture) is not sufficient to simulate the transfer phenomena occurring in living organisms, therefore, cell growth in a 3D space is desired. Drug absorption, distribution, metabolism, excretion and toxicity could be tested on 3D cell aggregates called spheroids, decrease the use of animal models and accelerate the drug development. In this work, the formation of spheroids from HT-29 human colorectal adenocarcinoma cells was successfully achieved by means of the so-called liquid marbles, which are liquid droplets encapsulated by a hydrophobic powder. During the cultivation in the medium inside the liquid marbles, cells spontaneously formed spherical agglomerates (spheroids) without the need of any supporting scaffold. The study focused on the influence of different parameters—namely liquid marble volume, seeding cell density and time of cultivation—on the final yield and quality of spheroids. This work has shown that using liquid marbles as microbioreactors is a suitable method for the cultivation of HT-29 cells in the form of spheroids. 相似文献
Peptide cation-radical fragment ions of the z-type, [●AXAR+], [●AXAK+], and [●XAR+], where X = A, C, D, E, F, G, H, K, L, M, N, P, Y, and W, were generated by electron transfer dissociation of peptide dications and investigated by MS3-near-ultraviolet photodissociation (UVPD) at 355 nm. Laser-pulse dependence measurements indicated that the ion populations were homogeneous for most X residues except phenylalanine. UVPD resulted in dissociations of backbone CO─NH bonds that were accompanied by hydrogen atom transfer, producing fragment ions of the [yn]+ type. Compared with collision-induced dissociation, UVPD yielded less side-chain dissociations even for residues that are sensitive to radical-induced side-chain bond cleavages. The backbone dissociations are triggered by transitions to second (B) excited electronic states in the peptide ion R-CH●-CONH- chromophores that are resonant with the 355-nm photon energy. Electron promotion increases the polarity of the B excited states, R-CH+-C●(O–)NH-, and steers the reaction to proceed by transfer of protons from proximate acidic Cα and amide nitrogen positions.
Electron capture dissociation (ECD) was studied with doubly charged dipeptide ions that were tagged with fixed-charge tris-(2,4,6-trimethoxyphenyl)phosphonium-methylenecarboxamido (TMPP-ac) groups. Dipeptides GK, KG, AK, KA, and GR were each selectively tagged with one TMPP-ac group at the N-terminal amino group while the other charge was introduced by protonation at the lysine or arginine side-chain groups to give (TMPP-ac-peptide + H)(2+) ions by electrospray ionization. Doubly tagged peptide derivatives were also prepared from GK, KG, AK, and KA in which the fixed-charge TMPP-ac groups were attached to the N-terminal and lysine side-chain amino groups to give (TMPP-ac-peptide-ac-TMPP)(2+) dications by electrospray. ECD of (TMPP-ac-peptide + H)(2+) resulted in 72% to 84% conversion to singly charged dissociation products while no intact charge-reduced (TMPP-ac-dipeptide + H)(+) ions were detected. The dissociations involved loss of H, formation of (TMPP + H)(+), and N-C(alpha) bond cleavages giving TMPP-CH(2)CONH(2)(+) (c(0)) and c(1) fragments. In contrast, ECD of (TMPP-ac-peptide-ac-TMPP)(2+) resulted in 31% to 40% conversion to dissociation products due to loss of neutral TMPP molecules and 2,4,6-trimethoxyphenyl radicals. No peptide backbone cleavages were observed for the doubly tagged peptide ions. Ab initio and density functional theory calculations for (Ph(3)P-ac-GK + H)(2+) and (H(3)P-ac-GK + H)(2+) analogs indicated that the doubly charged ions contained the lysine side-chain NH(3)(+) group internally solvated by the COOH group. The distance between the charge-carrying phosphonium and ammonium atoms was calculated to be 13.1-13.2 A in the most stable dication conformers. The intrinsic recombination energies of the TMPP(+)-ac and (GK + H)(+) moieties, 2.7 and 3.15 eV, respectively, indicated that upon electron capture the ground electronic states of the (TMPP-ac-peptide + H)(+*) ions retained the charge in the TMPP group. Ground electronic state (TMPP-ac-GK + H)(+*) ions were calculated to spontaneously isomerize by lysine H-atom transfer to the COOH group to form dihydroxycarbinyl radical intermediates with the retention of the charged TMPP group. These can trigger cleavages of the adjacent N-C(alpha) bonds to give rise to the c(1) fragment ions. However, the calculated transition-state energies for GK and GGK models suggested that the ground-state potential energy surface was not favorable for the formation of the abundant c(0) fragment ions. This pointed to the involvement of excited electronic states according to the Utah-Washington mechanism of ECD. 相似文献