Wrocław University of Technology

About: Wrocław University of Technology is a education organization based out in Wrocław, Poland. It is known for research contribution in the topics: Laser & Computer science. The organization has 13115 authors who have published 31279 publications receiving 338694 citations.

Synthesis and structure-activity relationship of methyl-substituted indolo[2,3-b]quinolines: novel cytotoxic, DNA topoisomerase II inhibitors.

Abstract: In furtherance of our SAR study on the chemistry and antitumor activity of fused nitrogen heteroaromatic compounds, a series of linear, methyl-substituted derivatives of 5H- and 6H-indolo[2,3-b]quinolines were synthesized according to the modified Graebe-Ullmann reaction. To establish the relationship between the physicochemical and biological activities of indolo[2,3-b]quinolines, their lipophilic properties, cytotoxic and antimicrobial activity, and ability to induce topoisomerase II dependent pSP65 DNA cleavage in vitro were investigated. We found that the antimicrobial and cytotoxic activity of indolo[2,3-b]quinolines was strongly influenced by the position, and the number of methyl substituents and the presence of methyl group at pyridine nitrogen was essential for the cytotoxicity of these compounds. All indolo[2,3-b]quinolines belonging to the 5H series, i.e., bearing a methyl group on the pyridine nitrogen, showed significant activity against procaryotic and eucaryotic organisms. They inhibited the growth of Gram-positive bacteria and pathogenic fungi at MIC range 3 x 10(-2) to 2.5 x 10(-1) mumol/mL, displayed cytotoxicity against KB cells ID50 in the range 2 x 10(-3) to 9 x 10(-3) mumol/mL, and stimulated the formation of calf thymus topoisomerase II mediated DNA cleavage at concentration between 0.4 and 10 microM. None of the indolo[2,3-b]quinolines belonging to the 6H series, i.e., lacking a methyl group on the pyridine nitrogen, was active in analogous tests. Of the investigated compounds, the most active was 2,5,9,11-tetramethyl-5H-indolo[2,3-b]quinoline, a compound bearing the highest number of symmetrically distributed methyl groups. The interaction of indolo[2,3-b]quinolines with DNA was studied by measuring the increase of calf thymus DNA denaturating temperature (Tm). The delta Tm values for the 5H series were found to be about 10 times as high as those for the 6H compounds. Indolo[2,3-b]quinolines with the highest number of methyl groups had the greatest contribution to the increase in the Tm of calf thymus DNA. The values of delta Tm reached 19 degrees C and 1.6 degrees C for the most substituted compounds of both series.

Evaluation of PLA–lignin bioplastics properties before and after accelerated weathering

Abstract: Two types of lignin obtained from softwood (LB) and hardwood (LO) were employed for manufacturing polylactic acid (PLA) – based composites. The morphological changes, mechanical and thermal properties, as well as water uptake of composites were evaluated before and after accelerated weathering. The chemical structure of lignin has an important influence on the composite properties. The addition of lignins to PLA matrix determined an increase of the impact strength and thermal stability of PLA, a good adhesion being observed in SEM micrographs. After accelerated weathering, tensile and impact strength decreased for all samples, but slightly for PLA/lignin composites, while all composites recorded an increase of water sorption capacity, especially for PLA/LB material. The free surface energy increased after weathering for all materials. The obtained results offer an opportunity to design environmentally friendly materials containing lignin that present higher values than the raw material itself.

How short can the H...H intermolecular contact be? New findings that reveal the covalent nature of extremely strong interactions.

Abstract: Ab initio calculations at the MP2/6-311++G(d,p) and MP2/aug-cc-pVDZ//MP2/aug-cc-pVTZ levels have been performed for the following complexes: H2OH+···HBeH, H2OH+···HBeBeH, H2OH+···HBeF, HClOH+···HB...

Estimates of Green Function for Relativistic α-Stable Process

Abstract: We call an R d -valued stochastic process X t with characteristic function exp {−t{(m 2/α+ξ2)α/2−m}},ξ∈R d ,m>0, the relativistic α-stable process In the paper we derive sharp estimates for the Green function of the relativistic α-stable process on C 1,1 domains Using these estimates we provide lower and upper bounds for the Poisson kernel As another application we derive 3G Theorem and Boundary Harnack Principle for C 1,1 domains