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81.
Natalia CZUMA Wojciech FRANUS Pawe BARAN WIK Agnieszka Katarzyna ZARBSKA 《Turkish Journal of Chemistry》2020,44(1):155
In the presented study, the sulfur dioxide sorption properties of fly ash zeolite X were investigated. Sorption tests were performed on fly ash zeolite samples that were not prepared specially for sorption, in addition to dried samples and samples in the presence of water vapor. The samples saturated with water vapor showed the highest sorption capacity. The sorption capacity of the samples additionally dried prior to the sorption experiment was higher than that of the samples that were not specially prepared for the sorption test. Regeneration tests indicated relatively good regeneration properties. The obtained results were described with the use of Langmuir, Sips, and Dubinin–Astakhov models, with the Dubinin–Astakhov model providing the best fit. 相似文献
82.
Joanna Bojarska Milan Remko Izabela D. Madura Krzysztof Kaczmarek Janusz Zabrocki Wojciech M. Wolf 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(4):328-345
Recently, fluorenylmethoxycarbonyl (Fmoc) amino acids (e.g. Fmoc–tyrosine or Fmoc–phenylalanine) have attracted growing interest in biomedical research and industry, with special emphasis directed towards the design and development of novel effective hydrogelators, biomaterials or therapeutics. With this in mind, a systematic knowledge of the structural and supramolecular features in recognition of those properties is essential. This work is the first comprehensive summary of noncovalent interactions combined with a library of supramolecular synthon patterns in all crystal structures of amino acids with the Fmoc moiety reported so far. Moreover, a new Fmoc‐protected amino acid, namely, 2‐{[(9H‐fluoren‐9‐ylmethoxy)carbonyl](methyl)amino}‐3‐{4‐[(2‐hydroxypropan‐2‐yl)oxy]phenyl}propanoic acid or N‐fluorenylmethoxycarbonyl‐O‐tert‐butyl‐N‐methyltyrosine, Fmoc‐N‐Me‐Tyr(t‐Bu)‐OH, C29H31NO5, was successfully synthesized and the structure of its unsolvated form was determined by single‐crystal X‐ray diffraction. The structural, conformational and energy landscape was investigated in detail by combined experimental and in silico approaches, and further compared to N‐Fmoc‐phenylalanine [Draper et al. (2015). CrystEngComm, 42 , 8047–8057]. Geometries were optimized by the density functional theory (DFT) method either in vacuo or in solutio. The polarizable conductor calculation model was exploited for the evaluation of the hydration effect. Hirshfeld surface analysis revealed that H…H, C…H/H…C and O…H/H…O interactions constitute the major contributions to the total Hirshfeld surface area in all the investigated systems. The molecular electrostatic potentials mapped over the surfaces identified the electrostatic complementarities in the crystal packing. The prediction of weak hydrogen‐bonded patterns via Full Interaction Maps was computed. Supramolecular motifs formed via C—H…O, C—H…π, (fluorenyl)C—H…Cl(I), C—Br…π(fluorenyl) and C—I…π(fluorenyl) interactions are observed. Basic synthons, in combination with the Long‐Range Synthon Aufbau Modules, further supported by energy‐framework calculations, are discussed. Furthermore, the relevance of Fmoc‐based supramolecular hydrogen‐bonding patterns in biocomplexes are emphasized, for the first time. 相似文献
83.
Ewa esawska Izabela Korona-Gowniak Wojciech Nitek Waldemar Tejchman 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(4):359-366
Derivatives of pyrimidine‐2(1H)‐selenone are a group of compounds with very strong antimicrobial activity. In order to study the effect of the position of the methoxy substituent on biological activity, molecular geometry and intermolecular interactions in the crystal, three derivatives were prepared and evaluated with respect to their antimicrobial activities, and their crystal structures were determined by X‐ray diffraction. The investigated compounds, namely, 1‐(X‐methoxyphenyl)‐4‐methyl‐6‐phenylpyrimidine‐2(1H)‐selenones (X = 2, 3 and 4 for 1 , 2 and 3 , respectively), C18H16N2OSe, showed very strong activity against selected strains of Gram‐positive bacteria and fungi. Two compounds, 1 and 2 , crystallize in the monoclinic space group P21/c, while 3 crystallizes in the space group P21/n; 1 has two molecules in the asymmetric unit and the other two ( 2 and 3 ) have one molecule. The geometries of the investigated compounds differ slightly in the mutual orientations of the aromatic and pyrimidineselenone rings. The O atom in 1 stabilizes the conformation of the molecules via intramolecular C—H…O hydrogen bonding. The packing of molecules is determined by weak C—H…N and C—H…Se intermolecular interactions and additionally in 1 and 2 by C—H…O intermolecular interactions. The introduction of the methoxy substituent results in greater selectivity of the investigated compounds. 相似文献
84.
Władysław Wilczyński Wojciech Wojdowski 《Central European Journal of Mathematics》2011,9(5):1057-1066
Ψ-density point of a Lebesgue measurable set was introduced by Taylor in [Taylor S.J., On strengthening the Lebesgue Density
Theorem, Fund. Math., 1958, 46, 305–315] and [Taylor S.J., An alternative form of Egoroff’s theorem, Fund. Math., 1960, 48,
169–174] as an answer to a problem posed by Ulam. We present a category analogue of the notion and of the Ψ-density topology.
We define a category analogue of the Ψ-density point of the set A at a point x as the Ψ-density point at x of the regular open representation of A. 相似文献
85.
86.
87.
88.
Wojciech Szymanski 《Proceedings of the American Mathematical Society》2002,130(5):1391-1399
It is shown that if is a countable, transitive directed graph with finitely many vertices, then is semiprojective.
89.
Quantum Spheres and Projective Spaces as Graph Algebras 总被引:5,自引:0,他引:5
The C
*
-algebras of continuous functions on quantum spheres, quantum real projective spaces, and quantum complex projective spaces
are realized as Cuntz-Krieger algebras corresponding to suitable directed graphs. Structural results about these quantum spaces,
especially about their ideals and K-theory, are then derived from the general theory of graph algebras. It is shown that the quantum even and odd dimensional
spheres are produced by repeated application of a quantum double suspension to two points and the circle, respectively.
Received: 31 January 2001 / Accepted: 29 July 2002 Published online: 7 November 2002
RID="*"
ID="*" Supported by grant No. R04–2001–000–00117–0 from the Korea Science & Engineering Foundation.
RID="**"
ID="**" Partially supported by the Research Management Committee of the University of Newcastle. 相似文献
90.
Koziołkiewicz M Owczarek A Wójcik M Domański K Guga P Stec WJ 《Journal of the American Chemical Society》2002,124(17):4623-4627
A new method of analysis has allowed the exonucleolytic cleavage by human 3'-exonuclease to be determined. Hydrolysis by human plasma 3'-exonuclease proceeds with retention of configuration at phosphorus. The new method determines the sense of chirality at phosphorus in isotopomeric adenosine 5'-O-[(18)O]phosphorothioates. This is based on stereospecific two-step conversion of the mono-thionucleotide into the corresponding deoxyadenosine 5'-O-alpha-[(18)O]thiotriphosphate, followed by the use of terminal deoxyribonucleotidyl transferase and MALDI TOF mass spectrometry of the resulting elongated primer. Retention of configuration in the reaction of plasma 3'-exonuclease implies a two-step mechanism with two displacements on phosphorus. Inversion at each step leads to overall retention. 相似文献