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991.
Azothia- and Azoxythiacrown Ethers as Ion Carriers. Part II. Anionic Response of Membrane Electrodes
Katarzyna Wygladacz Elzbieta Malinowska Jolanta Szcztygelska-Tao Jan F. Biernat 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(3-4):309-314
Ion-selective electrodes with plasticized poly(vinyl chloride) membranes containing 13-membered azothia- and azoxythiacrown ether complexes with silver, mercury or copper ions have been investigated. The potentiometric response towards various anions was studied. For membranes based on azothiacrown ether (B) complexes the following selectivity patterns were found:I- > SCN-, Br- > Cl- ClO4
- > salicylate, NO3
- (complex B with silver), I- > ClO4
- > SCN-, Br- > salicylate > Cl-, NO3
- (complex B with mercury) and SCN- > I- > Br- > ClO4
- > Cl- > salicylate > NO3
- (complex B with copper). For azoxythiacrown ether (A) only membranes containing its complex with mercury exhibited pronounced anion response and the selectivity pattern was similar to that observed for complex B with mercury. The origin of the anion response has been discussed. 相似文献
992.
993.
Katarzyna
lepokura Tadeusz Lis Magorzata Bogucka Joanna Lutomska Adam Kraszewski Krzysztof Sierosawski 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(7):o405-o409
The crystal structures of triethylammonium adenosine cyclic 2′,3′‐phosphate {systematic name: triethylammonium 4‐(6‐aminopurin‐9‐yl)‐6‐hydroxymethyl‐2‐oxido‐2‐oxoperhydrofurano[3,4‐c][1,3,2]dioxaphosphole}, Et3NH(2′,3′‐cAMP) or C6H16N+·C10H11N5O6P−, (I), and guanosine cyclic 2′,3′‐phosphate monohydrate {systematic name: triethylammonium 6‐hydroxymethyl‐2‐oxido‐2‐oxo‐4‐(6‐oxo‐1,6‐dihydropurin‐9‐yl)perhydrofurano[3,4‐c][1,3,2]dioxaphosphole monohydrate}, [Et3NH(2′,3′‐cGMP)]·H2O or C6H16N+·C10H11N5O7P−·H2O, (II), reveal different nucleobase orientations, viz. anti in (I) and syn in (II). These are stabilized by different inter‐ and intramolecular hydrogen bonds. The structures also exhibit different ribose ring puckering [4E in (I) and 3T2 in (II)] and slightly different 1,3,2‐dioxaphospholane ring conformations, viz. envelope in (I) and puckered in (II). Infinite ribbons of 2′,3′‐cAMP− and helical chains of 2′,3′‐cGMP− ions, both formed by O—H⋯O, N—H⋯X and C—H⋯X (X = O or N) hydrogen‐bond contacts, characterize (I) and (II), respectively. 相似文献
994.
Katarzyna Michalik Zofia Drzazga Anna Michnik 《Journal of Thermal Analysis and Calorimetry》2008,93(2):521-526
A study of 2′,3′-dideoxyinosine (ddI) stability and its interaction with human serum albumin (HSA) was carried out by differential
scanning microcalorimetry DSC. Scan rate dependent and irreversible endothermic thermal degradation of ddI was analyzed with
use of kinetic approach. Observed process could be interpreted in terms of simple first-order one step kinetic model. Moreover
it was shown that ddI bound weakly to the human serum albumin and stabilized this protein. 相似文献
995.
Stuart M. Macdonald Katarzyna Szot Joanna Niedziolka Frank Marken Marcin Opallo 《Journal of Solid State Electrochemistry》2008,12(3):287-293
A hydrophilic carbon nanoparticle–sol-gel electrode with good electrical conductivity within the sol-gel matrix is prepared.
Sulfonated carbon nanoparticles with high hydrophilicity and of 10–20 nm diameter (Emperor 2000) are co-deposited onto tin-doped
indium oxide substrates employing a sol-gel technique. The resulting carbon nanoparticle-sol-gel composite electrodes are
characterized as a function of composition and salt (KCl) additive. Scanning electron microscopy and voltammetry in the absence
and in the presence of a solution redox system suggest that the composite electrode films can be made electrically conducting
and highly porous to promote electron transport and transfer. The effect of the presence of hydrophilic carbon nanoparticles
is explored for the following processes: (1) double layer charging, (2) diffusion and adsorption of the electrochemically
reversible solution redox system 1,1′-ferrocenedimethanol, (3) electron transfer to the electrochemically irreversible redox
system hydrogen peroxide, and (4) electron transfer to the redox liquid tert-butylferrocene deposited into the porous composite
electrode film. The extended electrochemically active hydrophilic surface area is beneficial in particular for surface sensitive
processes (1) and (3), and it provides an extended solid|organic liquid|aqueous solution boundary for reaction (4). The carbon
nanoparticle–sol-gel composite electrodes are optimized to provide good electrical conductivity and to remain stable during
electrochemical investigation. 相似文献
996.
In this work, the Langmuir monolayer technique was applied to study the interactions between sphingomyelin and various sterols differing in the structure of the side chain (cholesterol, beta-sitosterol, stigmasterol). The mean area per molecule and the excess free energy of mixing values were analyzed in the context of sterol-induced condensing effect and interactions between molecules in the mixed monolayers. Moreover, the compression modulus values were calculated and widely discussed from the point of view of the ordering effect of sterols. It was found that all of the sterols investigated form the most stable monolayers with sphingomyelin at 2:1 sphingomyelin:sterol proportion and the strongest interactions exist between molecules in cholesterol-containing films. Moreover, cholesterol provokes the strongest area condensation and reveals the highest ordering properties, while plant sterols were found to differ only slightly with regards to their ordering properties. Additionally, the ordering effect of the sterols on dipalmitoylphosphatidylcholine (DPPC) films was analyzed and compared to that on sphingomyelin films. 相似文献
997.
Henryk Krawczyk Katarzyna Wsek Jacek Kdzia Jakub Wojciechowski Wojciech M. Wolf 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):o24-o26
The cyclopropane ring of the title compound, C17H16O2, shows a high level of substituent‐induced bond‐length asymmetry. The carboxyl group adopts a conformation that prompts electron‐density transfer from the ring towards the carbonyl π system. 相似文献
998.
Katarzyna Solarska-
ciuk Kinga Adach Sylwia Cyboran-Mikoajczyk Dorota Bonarska-Kujawa Agnieszka Rusak ucja Cwynar-Zajc Tomasz Machaowski Teofil Jesionowski Katarzyna Grzywacz Mateusz Fijakowski 《Molecules (Basel, Switzerland)》2021,26(5)
Silicon dioxide, in the form of nanoparticles, possesses unique physicochemical properties (size, shape, and a large surface to volume ratio). Therefore, it is one of the most promising materials used in biomedicine. In this paper, we compare the biological effects of both mesoporous silica nanoparticles extracted from Urtica dioica L. and pyrogenic material. Both SEM and TEM investigations confirmed the size range of tested nanoparticles was between 6 and 20 nanometers and their amorphous structure. The cytotoxic activity of the compounds and intracellular ROS were determined in relation to cells HMEC-1 and erythrocytes. The cytotoxic effects of SiO2 NPs were determined after exposure to different concentrations and three periods of incubation. The same effects for endothelial cells were tested under the same range of concentrations but after 2 and 24 h of exposure to erythrocytes. The cell viability was measured using spectrophotometric and fluorimetric assays, and the impact of the nanoparticles on the level of intracellular ROS. The obtained results indicated that bioSiO2 NPs, present higher toxicity than pyrogenic NPs and have a higher influence on ROS production. Mesoporous silica nanoparticles show good hemocompatibility but after a 24 h incubation of erythrocytes with silica, the increase in hemolysis process, the decrease in osmotic resistance of red blood cells, and shape of erythrocytes changed were observed. 相似文献
999.
Magorzata Gra Anna Czopek Anna Rapacz Anna Gbska Katarzyna Wjcik-Pszczoa Elbieta Pkala Krzysztof Kamiski 《Molecules (Basel, Switzerland)》2021,26(6)
The new series of 3-(2-chlorophenyl)- and 3-(3-chlorophenyl)-pyrrolidine-2,5-dione-acetamide derivatives as potential anticonvulsant and analgesic agents was synthesized. The compounds obtained were evaluated in the following acute models of epilepsy: maximal electroshock (MES), psychomotor (6 Hz, 32 mA), and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The most active substance-3-(2-chlorophenyl)-1-{2-[4-(4-fluorophenyl)piperazin-1-yl]-2-oxoethyl}-pyrrolidine-2,5-dione (6) showed more beneficial ED50 and protective index values than the reference drug—valproic acid (68.30 mg/kg vs. 252.74 mg/kg in the MES test and 28.20 mg/kg vs. 130.64 mg/kg in the 6 Hz (32 mA) test, respectively). Since anticonvulsant drugs are often effective in neuropathic pain management, the antinociceptive activity for two the promising compounds—namely, 6 and 19—was also investigated in the formalin model of tonic pain. Additionally, for the aforementioned compounds, the affinity for the voltage-gated sodium and calcium channels, as well as GABAA and TRPV1 receptors, was determined. As a result, the most probable molecular mechanism of action for the most active compound 6 relies on interaction with neuronal voltage-sensitive sodium (site 2) and L-type calcium channels. Compounds 6 and 19 were also tested for their neurotoxic and hepatotoxic properties and showed no significant cytotoxic effect. 相似文献
1000.
Joanna J. Sajkowska-Kozielewicz Pawe Kozielewicz Katerina Makarova Marcin Stocki Nicholas M. Barnes Katarzyna Paradowska 《Molecules (Basel, Switzerland)》2021,26(1)
A new alkaloid, geissospermiculatine was characterized in Geissospermum reticulatum A. H. Gentry bark (Apocynaceae). Here, following a simplified isolation protocol, the structure of the alkaloid was elucidated through GC-MS, LC-MS/MS, 1D, and 2D NMR (COSY, ROESY, HSQC, HMBC, 1H-15N HMBC). Cytotoxic properties were evaluated in vitro on malignant THP-1 cells, and the results demonstrated that the cytotoxicity of the alkaloid (30 μg/mL) was comparable with staurosporine (10 μM). Additionally, the toxicity was tested on zebrafish (Danio rerio) embryos in vivo by monitoring their development (0–72 h); toxicity was not evident at 30 μg/mL. 相似文献